From VBA Help -- AddNew
Note To add, edit, or delete a record, there must be a unique index on the record in the underlying data source. If not, a "Permission denied" error will occur on the AddNew, Delete, or Edit method call in a Microsoft Jet workspace, or an "Invalid argument" error will occur on the Update call in an ODBCDirect workspace.
Also, I think you need to specify the DAO recordset object as a dynaset when editing linked tables
Set rsClient = CurrentDb.OpenRecordset("dbo_tblClient", dbOpenDynaset)
OM Gang