MinGW, link to dll on Windows

I am trying to use a library I got from a camera vendor in a sample program. I have a .dll and .lib file for a library. My compilation command:

g++  -o "Win32App.exe" -L"..\..\SK develop\SK91GigE-WIN\Lib" obj/winmain.o obj/callbacks.o obj/resource.o -s -lcomctl32 -Wl,--subsystem,windows -lSK91GigE_x64

      

        
        
        
      

    

and I get:

obj/winmain.o:winmain.cpp:(.text+0x292): undefined reference to `SK_LOADDLL'
collect2.exe: error: ld returned 1 exit status

      

        
        
        
      

    

looking at .lib with nm shows:

BFD: SK91GigE_x64.lib(SK91GigE_x64.dll): Recognised but unhandled machine type (0x8664) in Import Library Format archive 
nm: SK91GigE_x64.dll: File format not recognized

      

        
        
        
      

    

and for DLL it produces:

nm: SK91GigE_x64.dll: File format not recognized

      

        
        
        
      

    

Any ideas on how I can change this lib to include it?