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

[ns2k]

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?