Implements Microsoft.Office.Core.Range Interface (VB.Net)

I tried to implements Microsoft.Office.Core.Range Interface, but the dot net raise errors :
+ ' '_Default' cannot implement '_Default' because there is no matching property on interface 'Range'.'
+ ' 'Item' cannot implement 'Item' because there is no matching property on interface 'Range'.'
+ ' 'Value' cannot implement 'Value' because there is no matching property on interface 'Range'.'

see my declarations in the class below :

Public Class RangeClass
Implements Excel.Range
.................

all kind of properties and functions that were inserted automatic by the dot net

.................

Public Overridable Property _Default(Optional ByVal RowIndex As Object = Nothing, Optional ByVal ColumnIndex As Object = Nothing) As Object Implements Excel.Range._Default
Get
End Get
Set(ByVal newValue As Object)
End Set
End Property

Public Property Item(ByVal RowIndex As Object, Optional ByVal ColumnIndex As Object = Nothing) As Object Implements Excel.Range.Item
Get
End Get
Set(ByVal newValue As Object)
End Set
End Property

Public Property Value(Optional ByVal RangeValueDataType As Object = Nothing) As Object Implements Excel.Range.Value
Get
End Get
Set(ByVal newValue As Object)
End Set
End Property
End Class

What is the reason for that?