I have a Qt program that needs to use two C libraries. One of them I can call functions from and it works fine. The other one, when I add a call to a function in that library, the program won't run in the ide. The process stub window comes up with no qDebug output and the application does not run. Both library files are dlls - I am running under Windows. Both libraries look ok in dependency checker.
They are both set up the same way in the pro file.

Qt Code: 
  1. DEPENDPATH += C:/development/QT_Projects/HRLogger_Dev_Spots/debug/Hamlib
  2. INCLUDEPATH += C:/development/QT_Projects/HRLogger_Dev_Spots/debug/Hamlib
  3. LIBS += -L"C:/development/QT_Projects/HRLogger_Dev_Spots/debug/Hamlib"
  4. LIBS += -llibhamlib
  5.  
  6.  
  7. DEPENDPATH += "C:/development/qt_projects/hrlogger_dev_spots/debug/tqsllib/include"
  8. INCLUDEPATH += "C:/development/qt_projects/hrlogger_dev_spots/debug/tqsllib/include"
  9. LIBS += -L"C:/development/QT_Projects/HRLogger_Dev_Spots/debug/tqsllib/lib"
  10. LIBS += -ltqsllib2
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Headers for both libraries are included:
Qt Code: 
  1. extern "C"
  2. {
  3.     #include "tqsllib.h"
  4.     #include "tqslerrno.h"
  5.     #include "tqslconvert.h"
  6.     #include "adif.h"
  7. }
  8.  extern "C" {
  9.     #include "rig.h"
  10.     #include "rig_dll.h"
  11.     #include "riglist.h"
  12.     #include "rigclass.h"
  13.     #include "rotator.h"
  14.     #include "rotlist.h"
  15.     }
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libhamlib works fine with my program. tqsllib2 causes it not to run. Makes no difference where in my program I put a call to a function in tqsllib2, even though that code is not executed at startup, my application fails to run. This happens with either the tqsllib I compiled using gcc, or the tqsllib file that is supplied with the windows application that uses the library.

Probably some simple explanation but I can't see it.