编译报错:unresolved external symbol,求助!!

我在vc++60的集成环境中编译程序时，提示出错信息如下：--------------------Configuration: ip - Win32 Debug--------------------
Compiling...
ipDlg.cpp
Linking...
ipDlg.obj : error LNK2001: unresolved external symbol _Netbios@4
Debug/ip.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.ip.exe - 2 error(s), 0 warning(s)请教，我该如何排错，谢谢！！！！
附:已经包含"#include <Nb30.h>"