OPC/DCOM issues

I am using a windows 2003 Server running an OPC server and client (different vendors for the server and client). I can’t create any groups in the OPC server when I try and connect using the OPC client tool. I’ve set all the required permissions/access levels as per the OPC foundations white paper, and other documentation (Matrikon, etc).

Does anyone have any ideas why the OPC server won’t allow me to create a group using the OPC client? I can only think there is some issue with DCOM, but I’m stuffed if I know what it could be. Help please!!!