OPC, CWinThread Message and CO_E_NOTINITIALIZED

Hello,
I hope someone can help me

I access a OPC server from a multothreaded application. The class who comunicate with the server
is used (and has an instance) in only one CWinThread (opcThread). 2 threads are accessing opcThread.
If I use a message (PostThreadMessage) to send orders to opcThread, the communication with the
server give me a CO_E_NOTINITIALIZED error message (0x800401F0). If I call directly a function
of opcThread, all is working fine.

Please, help me

Thank's


Bernie