asp.net调用DLL问题!

dll函数:
CString _declspec(dllexport) AutoNumber(CString sTable, CString sFieldName, CString sCode, CString nStyle)
{
AfxMessageBox(sTable);
AfxMessageBox(sFieldName);
AfxMessageBox(sCode);
AfxMessageBox(nStyle);
return sTable;
}
ASP.NET调用
string strdd;
strdd=DLLClass.AutoNumber("de","id","n","2");运行之后是显示的值是这样的.
id,n,2,乱码
最后是程序崩溃...
de怎么没了?
请问是怎么回事?