Custom datasourcekey

   I have just upgraded to 3.6.5.4. Now my custom datasourcekeyresolver in Apphelper no longer compiles.
I get errors:

Error    39    Class 'MyDataSourceKeyResolver' must implement 'Function GetKey(pKeyName As String, pKeyExtension As String) As Util.IDataSourceKey' for interface 'IdeaBlade.Persistence.IDataSourceKeyResolver'.    C:\Documents and Settings\Administrator.TIMPEXAS\My Documents\Visual Studio Projects\larserik\skanning_trunk\src\ScanFrbClient_lok\AppHelper\MyDataSourceKeyResolver.vb    6    51    AppHelper

Error    40    'GetKey' cannot implement 'GetKey' because there is no matching function on interface 'IdeaBlade.Persistence.IDataSourceKeyResolver'.    C:\Documents and Settings\Administrator.TIMPEXAS\My Documents\Visual Studio Projects\larserik\skanning_trunk\src\ScanFrbClient_lok\AppHelper\MyDataSourceKeyResolver.vb    9    129    AppHelper

This is my code:
Imports IdeaBlade.Persistence
Imports IdeaBlade.Util
Imports IdeaBlade.Rdb

<Serializable()> _
Public Class MyDataSourceKeyResolver : Implements IDataSourceKeyResolver

    Public Function GetKey(ByVal pKeyName As String, ByVal pKeyExtension As String) As IdeaBlade.Util.IDataSourceKey Implements IdeaBlade.Persistence.IDataSourceKeyResolver.GetKey
        If (pKeyExtension.ToLower() <> "default") Then

            Dim connectionString As String = pKeyExtension
            Return New IdeaBlade.Rdb.RdbKey(pKeyName, connectionString)
        Else
            Return Nothing ' Didn't build key; DefaultDataSourceKeyResolver takes over
        End If

    End Function

End Class