error LNK2001: unresolved external symbol "declspec(dllimport) const ShowBmpDl解决方法

error LNK2001: unresolved external symbol "__declspec(dllimport) const ShowBmpDl
我创建了一个MFC动态链接库，但链接时报错
Linking...
  Creating library Debug/ShowBmpDll.lib and object Debug/ShowBmpDll.exp
ShowBmpDllClass1.obj : error LNK2001: unresolved external symbol "__declspec(dllimport) const ShowBmpDllClass::`vftable'" (__imp_??_7ShowBmpDllClass@@6B@)
Debug/ShowBmpDll.dll : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

ShowBmpDll.dll - 2 error(s), 5 warning(s)
请问怎么解决啊？

------解决方案--------------------
你的lib导出文件路径都设置好了吗

http://blog.****.net/bao_qibiao/archive/2009/09/09/4536033.aspx
------解决方案--------------------
lib没包含进去