谁指点下这是什么错误

unresolved external symbol "public: void __thiscall CGDbLayer::CLButton::FromRecordset(class CGDbLayer::CADORecordset &)" (?FromRecordset@CLButton@CGDbLayer@@QAEXAAVCADORecordset@2@@Z)
../../bin/DebugA/LDbVisitTestda.exe : fatal error LNK1120: 1 unresolved externals这是什么错误？是没定义好么还是什么才学不太懂帮帮忙谢谢了