Inheriting a generic Class based on Generic Interface

[simrim1]

I want to define a generic interface which will be implemented by an abstract Generic Class. Basically this generic class is a collection class of any class.

Interfaces are in a separate project saved as FileReconciliation.

Here are the interface definitions

Imports System.Collections

Public Interface ICollectionCommon(Of T As Class)
    Inherits IEnumerable
    Function Exists(ByVal oKey As Object) As Boolean
    ReadOnly Property Count() As Long
    Sub Remove(ByVal oKey As Object)
    Function Add(Optional ByVal oObject As T = Nothing, Optional ByVal sKey As String = "") As T
    Default ReadOnly Property Item(ByVal oKey As Object) As T
End Interface

Public Interface ITag
    Property Tag() As String
    Property TagValue() As String
End Interface

Public Interface ITransaction
    Property Tags() As ICollectionCommon(Of ITag)
End Interface

Public Interface IFileInformation
    ReadOnly Property FileName() As String
    ReadOnly Property FileType() As FileType
    ReadOnly Property BICForwardingBank() As String
    ReadOnly Property BICExecutingBank() As String
    ReadOnly Property GetFileLevelTags() As ICollectionCommon(Of ITag)
    ReadOnly Property TimeStamp() As String
    ReadOnly Property Transactions() As ICollectionCommon(Of ITransaction)
    Sub GetFileInfo(ByVal sFileName As String)
End Interface

Public Enum FileType
    frFileTypeUnknown
    frFileTypeDriectDebit
    frFileTypeDirectCredit
End Enum

Here is the code for CollectionClass which implements ICollectionCommon

Imports FileReconciliation

Public MustInherit Class CollectionClass(Of AnyObject As {Class, New})
    Implements ICollectionCommon(Of AnyObject)

    Private clnCollectionOfOjects As Collection

    Public Function Add(Optional ByVal oAnyObject As AnyObject = Nothing, Optional ByVal sKey As String = "") As AnyObject Implements ICollectionCommon(Of AnyObject).Add
        Dim objNewMember As AnyObject
        If oAnyObject Is Nothing Then
            objNewMember = New AnyObject
        Else
            objNewMember = oAnyObject
        End If
        If sKey.Trim().Length = 0 Then
            clnCollectionOfOjects.Add(objNewMember)
        Else
            clnCollectionOfOjects.Add(objNewMember, sKey)
        End If
        Return objNewMember
    End Function

    Public ReadOnly Property Count() As Long Implements ICollectionCommon(Of AnyObject).Count
        Get
            Count = clnCollectionOfOjects.Count
        End Get
    End Property

    Public Function Exists(ByVal oKey As Object) As Boolean Implements ICollectionCommon(Of AnyObject).Exists
        If clnCollectionOfOjects(oKey) Is Nothing Then
            Return False
        Else
            Return True
        End If
    End Function

    Default Public ReadOnly Property Item(ByVal oKey As Object) As AnyObject Implements ICollectionCommon(Of AnyObject).Item
        Get
            Item = clnCollectionOfOjects(oKey)
        End Get
    End Property

    Public Sub Remove(ByVal oKey As Object) Implements ICollectionCommon(Of AnyObject).Remove
        clnCollectionOfOjects.Remove(oKey)
    End Sub

    Public Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator
        GetEnumerator = clnCollectionOfOjects.GetEnumerator
    End Function

    Public Sub New()
        clnCollectionOfOjects = New Collection
    End Sub

    Protected Overrides Sub Finalize()
        clnCollectionOfOjects = Nothing
    End Sub
End Class

Other Classes based on other interfaces are as follows

Imports FileReconciliation

Public Class clsFileInformation1
    Implements IFileInformation

    Dim strFileName As String
    Dim intFileType As FileType
    Dim strBICForwardingBank As String
    Dim strBICExecutingBank As String
    Dim strTimeStamp As String
    Dim objFileLevelTags As clsTags
    Dim objTransactions As clsTransactions

    Public Sub New()
        objFileLevelTags = New clsTags()
        objTransactions = New clsTransactions()
    End Sub

    Protected Overrides Sub Finalize()
        objFileLevelTags = Nothing
        objTransactions = Nothing
        MyBase.Finalize()
    End Sub

    Public ReadOnly Property BICExecutingBank() As String Implements FileReconciliation.IFileInformation.BICExecutingBank
        Get
            BICExecutingBank = strBICExecutingBank
        End Get
    End Property

    Public ReadOnly Property BICForwardingBank() As String Implements FileReconciliation.IFileInformation.BICForwardingBank
        Get
            BICForwardingBank = strBICForwardingBank
        End Get
    End Property

    Public ReadOnly Property FileName() As String Implements FileReconciliation.IFileInformation.FileName
        Get
            FileName = strFileName
        End Get
    End Property

    Public ReadOnly Property FileType() As FileReconciliation.FileType Implements FileReconciliation.IFileInformation.FileType
        Get
            FileType = intFileType
        End Get
    End Property

    Public Sub GetFileInfo(ByVal sFileName As String) Implements FileReconciliation.IFileInformation.GetFileInfo
        Dim objTransaction As clsTransaction
        Dim objTag As clsTag
        Dim objTags As clsTags
        strFileName = sFileName
        objTags = New clsTags()
        objTag = objTags.Add()
        objTag.Tag = ":20:"
        objTag.TagValue = ":20: Value"
        objTag = objTags.Add(sKey:=":30:")
        objTag.Tag = ":30:"
        objTag.TagValue = ":30: Value"
        objTransaction = objTransactions.Add()
        objTransaction.Tags = objTags  'exception is thrown here
        objFileLevelTags = objTags
    End Sub

    Public ReadOnly Property GetFileLevelTags() As FileReconciliation.ICollectionCommon(Of FileReconciliation.ITag) Implements FileReconciliation.IFileInformation.GetFileLevelTags
        Get
            GetFileLevelTags = objFileLevelTags
        End Get
    End Property

    Public ReadOnly Property TimeStamp() As String Implements FileReconciliation.IFileInformation.TimeStamp
        Get
            TimeStamp = strTimeStamp
        End Get
    End Property

    Public ReadOnly Property Transactions() As FileReconciliation.ICollectionCommon(Of FileReconciliation.ITransaction) Implements FileReconciliation.IFileInformation.Transactions
        Get
            Transactions = objTransactions
        End Get
    End Property
End Class

Public Class clsFilesInformation
    Inherits CollectionClass(Of clsFileInformation1)

    Public Sub New()
        MyBase.New()
    End Sub
End Class

Public Class clsTag
    Implements ITag

    Private strTagID As String
    Private strTagValue As String

    Public Sub New()
        strTagID = ""
        strTagValue = ""
    End Sub

    Friend Sub New(ByVal sTagID As String)
        strTagID = sTagID
        strTagValue = ""
    End Sub

    Friend Sub New(ByVal sTagID As String, ByVal sTagValue As String)
        strTagID = sTagID
        strTagValue = sTagValue
    End Sub

    Public Property Tag() As String Implements ITag.Tag
        Get
            Tag = strTagID
        End Get
        Friend Set(ByVal value As String)
            strTagID = value
        End Set
    End Property

    Public Property TagValue() As String Implements ITag.TagValue
        Get
            TagValue = strTagValue
        End Get
        Friend Set(ByVal value As String)
            strTagValue = value
        End Set
    End Property
End Class

Public Class clsTags
    Inherits CollectionClass(Of clsTag)

    Public Sub New()
        MyBase.New()
    End Sub
End Class

Public Class clsTransaction
    Implements ITransaction
    Dim objTags As clsTags

    Public Property Tags() As ICollectionCommon(Of ITag) Implements ITransaction.Tags
        Get
            Tags = objTags
        End Get
        Set(ByVal value As ICollectionCommon(Of ITag))
            objTags = value
        End Set
    End Property
End Class

Public Class clsTransactions
    Inherits CollectionClass(Of clsTransaction)

    Public Sub New()
        MyBase.New()
    End Sub
End Class

Sub Main is follows in a separate module

Imports FileReconciliation

Module StartUP
    <STAThread()> _
    Sub Main()
        Dim objTags As clsTags
        Dim objFilesInformation As clsFilesInformation
        Dim objFileInformation As clsFileInformation1
        objFilesInformation = New clsFilesInformation
        objFileInformation = objFilesInformation.Add()
        objFileInformation.GetFileInfo("SomeFile")
        objTags = objFileInformation.GetFileLevelTags
        objFileInformation = Nothing
        objFilesInformation = Nothing
    End Sub
End Module

Line of code, in second last code section in Sub GetFileInfo, marked as Bold is where an error occurs.
Can somebody point out what I'm doing wrong?

GenericInterfaces.zip