ADO SQLSERVER2000 无法读取master中的信息

...
m_pCon->Open((_bstr_t)"driver={SQL Server};Server=127.0.0.1;DATABASE = master","","",adModeUnknown);//连接数据库   
....

try
{
    m_pCon->Open("DSN=master","","",0); 
    CString str_sql = "select name from master";
    BSTR bstrSQL = str_sql.AllocSysString(); 
    m_pRs->Open(bstrSQL,(IDispatch*)m_pCon,adOpenDynamic,adLockOptimistic,adCmdText);
    while(m_pRs->BOF)
    {
        _bstr_t TheValue=m_pRs->Fields->GetItem("name")->Value;
        CString StrValue = (char*)(_bstr_t)TheValue;
        MessageBox(StrValue);
        m_pRs->MoveNext();
    }
}显示错误为"对象打开时不允许操作",master不是只读的吗?怎么连读也不行了?还是我别的地方错了,求救.谢谢