Error MAPI_E_FAILONEPROVIDER from OpenMsgStore call.

Hi,

I am using Exchange MAPI DLL to access an Exchange Message Store, on Windows 2003. After the MAPILogonEx() login call (using an account and password with Admin Privileges), I attempt an OpenMessageStore() using something like this:

hrT = mapiSession->OpenMsgStore(
        (ULONG)0,
        lpRows->aRow->lpProps[0].Value.bin.cb,
        (LPENTRYID)lpRows->aRow->lpProps[0].Value.bin.lpb,
        NULL,
        MAPI_BEST_ACCESS |
        MDB_NO_DIALOG |
        MDB_TEMPORARY |
        MDB_NO_MAIL |
        MAPI_DEFERRED_ERRORS,
        lppMDB);

I've verified the Entry Id to be correct.

The above call fails with MAPI_E_FAILONEPROVIDER (8004011d) error code.

Any way to find out what the problem could be?

Thanks.