关于RAS的几点问题，恳求各位大虾留意，帮忙!!!!!!!!!!

[zhoutao]

请问各位大虾，我在RAS拨号之后，根据返回值得不到相应的错误提示，请大虾们务必帮帮我！！！
1.)通过下述办法，得不到相应的错误提示，为什么？
//指定的拨号连接。
if (dw = RasDial(NULL, NULL, ¶ms, NULL, NULL, &handle)!=0)
{
TCHAR szBuf[256];
memset(szBuf, NULL, 256);
RasGetErrorString( (UINT)dw, (LPSTR)szBuf, 256 );
AfxMessageBox( (LPSTR)szBuf, MB_OK and MB_ICONSTOP);
}
2.)通过下述办法，CALLBACK函数错误返回代码表谁有？

if (dw = RasDial(NULL, NULL, ¶ms, NULL, (RASDIALFUNC1)RasDialFunc, &handle)!=0)
VOID CALLBACK RasDialFunc(UINT unMsg, RASCONNSTATE rasconnstate, DWORD dwError)
{
switch (rasconnstate)
{
case RASCS_OpenPort:
case RASCS_PortOpened:
case RASCS_ConnectDevice:
case RASCS_DeviceConnected:
case RASCS_AllDevicesConnected:
case RASCS_Authenticate:
case RASCS_Connected = RASCS_DONE:
case RASCS_Disconnected:
// ...
}
3.)怎么调用拨号网络中“正在拨号“对话框？

[warmworm]

2
MSDN
PLATFORM SDK\NETWORKING AND DIRECTORY SERVICES\NETWORK COMMUNITCATIONS
3
RasEnumConnections