ISynchronize->Reset() fails with error result 0x80010120

Question

When I run the following code:

    ISynchronize *sync_p;
    res = CoCreateInstance(CLSID_StdEvent, NULL, CLSCTX_INPROC, IID_ISynchronize, (LPVOID *)&sync_p);
    if (!SUCCEEDED(res))
        _com_issue_error(res);
    res = sync_p->Reset();

The final line fails with error code 0x80010120 - "There are no synchronize objects to wait on". The documentation doesn't indicate anything about what might cause this error - it's almost as if it's getting things mixed up with ISynchronizeContainer. What am I doing wrong here?