error LNK2001 - help?

All of my OpenGL programming have been fine until reaching NeHe's lesson 6 tutorial. I try compiling it, and this came up.

Compiling...
OpenGL Practice.cpp
Linking...
OpenGL Practice.obj : error LNK2001: unresolved external symbol _auxDIBImageLoadA@4
Debug/OpenGL Practice.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

Any ideas?