Hi,
I'm converting some VB6 code to .NET and I'm having an error occur when I try to loop through a collection of objects:

'An unhandled exception of type 'System.InvalidCastException' occurred in SiD.exe

Additional information: Specified cast is not valid.'

It basically doesn't like the 'For Each' statement in the simplified code listing below:

Code:
Sub PopTreeView() 

    { Other Declarations } 
    Dim oServer As cServer 


    For Each oServer In gcolServers 

    { Processing Code } 
     
    Next 

 End Sub
The gcolServers variable is a collection of cServers, so its got me confused as to why the cast is invalid. As far as I understand it the enumeration within a collection is inherited in .NET so I don't need to code for it specifically like in VB6. Here's the object and collection definitions (simplified for space) anyhow:


Code:
Public Class cServer 

  ' Local variables to hold property values 
  ' 
  {Local variable defs} 


  {Property gets and sets} 


  Public Sub New(ByVal intServerID As Integer, _ 
                  ByVal strServerName As String, _ 
                  ByVal strServerDescription As String, _ 
                  ByVal intLocationID As Integer, _ 
                  ByVal intOSTypeID As Integer, _ 
                  ByVal strNotes As String, _ 
                  ByVal intModelTypeID As Integer, _ 
                  ByVal strSerialNumber As String, _ 
                  ByVal strSAPassword As String, _ 
                  ByVal strSystemAdminPassword As String, _ 
                  ByVal strSQLSSAPassword As String, _ 
                  ByVal strMachineAdminPassword As String, _ 
                  ByVal clDrives As colDrives, _ 
                  ByVal clDatabases As colDatabases, _ 
                  ByVal intGroupID As Integer, _ 
                  ByVal intGroupOrder As Integer, _ 
                  Optional ByVal bIsPwdDirty As Boolean = False, _ 
                  Optional ByVal bIsDetDirty As Boolean = False) 

    ServerID = intServerID 
    ServerName = strServerName 
    ServerDescription = strServerDescription 
    LocationID = intLocationID 
    OSTypeID = intOSTypeID 
    Notes = strNotes 
    ModelTypeID = intModelTypeID 
    SerialNumber = strSerialNumber 
    SAPassword = strSAPassword 
    SystemAdminPassword = strSystemAdminPassword 
    SQLSSAPassword = strSQLSSAPassword 
    MachineAdminPassword = strMachineAdminPassword 
    Drives = Drives 
    Databases = Databases 
    GroupID = intGroupID 
    GroupOrder = intGroupOrder 
    IsPwdDirty = IsPwdDirty 
    IsDetDirty = IsDetDirty 

  End Sub 

End Class 


Public Class colServers 

  Inherits System.Collections.DictionaryBase 

  Public Function Add(ByVal ServerID As Integer, _ 
                      ByVal ServerName As String, _ 
                      ByVal ServerDescription As String, _ 
                      ByVal LocationID As Integer, _ 
                      ByVal OSTypeID As Integer, _ 
                      ByVal Notes As String, _ 
                      ByVal ModelTypeID As Integer, _ 
                      ByVal SerialNumber As String, _ 
                      ByVal SAPassword As String, _ 
                      ByVal SystemAdminPassword As String, _ 
                      ByVal SQLSSAPassword As String, _ 
                      ByVal MachineAdminPassword As String, _ 
                      ByVal Drives As colDrives, _ 
                      ByVal Databases As colDatabases, _ 
                      ByVal IsDetDirty As Boolean, _ 
                      ByVal IsPwdDirty As Boolean, _ 
                      ByVal GroupID As Integer, _ 
                      ByVal GroupOrder As Integer, _ 
                      ByVal sKey As String) As cServer 

    Dim oServer As cServer 

    ' Add the properties to the collection as a new Server Class 
    ' 
    dictionary.Add(sKey, New cServer(ServerID, _ 
                                      ServerName, _ 
                                      ServerDescription, _ 
                                      LocationID, _ 
                                      OSTypeID, _ 
                                      Notes, _ 
                                      ModelTypeID, _ 
                                      SerialNumber, _ 
                                      SAPassword, _ 
                                      SystemAdminPassword, _ 
                                      SQLSSAPassword, _ 
                                      MachineAdminPassword, _ 
                                      Drives, _ 
                                      Databases, _ 
                                      GroupID, _ 
                                      GroupOrder, _ 
                                      IsDetDirty, _ 
                                      IsPwdDirty)) 

    ' Return the object created 
    ' 
    Return dictionary.Item(sKey) 

  End Function 


  Public Sub Remove(ByVal strKey As String) 

    ' remove the cServer Class from the collection for the supplied Key 
    ' 
    dictionary.Remove(strKey) 

  End Sub 


  Default Public Property Item(ByVal strKey As String) As cServer 

    Get 
      Return DirectCast(Dictionary.Item(strKey), cServer) 
    End Get 

    Set(ByVal Value As cServer) 
      Me.Dictionary.Item(strKey) = Value 
    End Set 

  End Property 

  Public Sub New() 

    MyBase.New() 

  End Sub 

End Class
Anyone got any suggestions?

Rob