LNK2019 errors - how do I get rid of them?

Working on a qt project using msvc2008 compiler. I copied some functions from an example project that runs just fine in visual studio 2008, but now I'm getting LNK2019 errors. I've looked around, and they seem to caused by the compiler not finding some kinda declaration?

The errors are:

trackerwindow.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) public: unsigned short const * __thiscall CPDIdev::GetLastResultStr(void)" (__imp_?GetLastResultStr@CPDIdev@@QAEPBGXZ) referenced in function "private: bool __thiscall trackerWindow::Connect(void)" (?Connect@trackerWindow@@AAE_NXZ)

and

trackerwindow.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall CPDIbiterr::Parse(unsigned short *,unsigned long)const " (__imp_?Parse@CPDIbiterr@@QBEXPAGK@Z) referenced in function "private: bool __thiscall trackerWindow:开发者_StackOverflow社区:SetupDevice(void)" (?SetupDevice@trackerWindow@@AAE_NXZ)

and

trackerwindow.obj:-1: error: LNK2019: unresolved external symbol "__declspec(dllimport) public: int __thiscall CPDIdev::StartPipeExport(unsigned short const *)" (__imp_?StartPipeExport@CPDIdev@@QAEHPBG@Z) referenced in function "private: bool __thiscall trackerWindow::SetupDevice(void)" (?SetupDevice@trackerWindow@@AAE_NXZ)

The CPDIdev class is from a library that the hardware I'm using uses, so i haven't written any of that code, and don't understand any of it.

I've got the following in the .pro file

INCLUDEPATH += D:\Patriot\Inc
LIBS += D:\Patriot\Lib\PDI.lib

and

#include "PDI.h"

in the header file (trackerwindow.h)... not really sure what declaration or include I'm missing...

Any ideas? Many thanks!

This means that you are missing a import library, .lib.