Failing to access a Windows DLL...

[marksummerfield]

I'm trying to access a DLL on Windows using the following code:
    
    
    import os
    
    let dll = joinPath(getAppDir(), "DebenuPDFLibrary64DLL1311.dll")
    
    type
      DPL* = object
        id: int32
    
    proc createLibrary(): int32 {.cdecl, dynlib: dll,
      importc: "DPLCreateLibrary".}
    proc releaseLibrary(id: int32): void {.cdecl, dynlib: dll,
      importc: "DPLReleaseLibrary".}
    
    proc newDPL*(): DPL =
      result.id = createLibrary()
    
    proc close*(dpl: DPL): void =
      if dpl.id != 0:
        releaseLibrary(dpl.id)
    
    if isMainModule:
      var dpl = newDPL()
      defer: dpl.close()
    

Here's what happens when I try to compile and run it: 
    
    
    R:\pdfpage>nim c -r debenu.nim
    Hint: used config file 'c:\bin\nim\config\nim.cfg' [Conf]
    Hint: system [Processing]
    Hint: debenu [Processing]
    Hint: os [Processing]
    Hint: strutils [Processing]
    Hint: parseutils [Processing]
    Hint: math [Processing]
    Hint: algorithm [Processing]
    Hint: times [Processing]
    Hint: winlean [Processing]
    Hint: dynlib [Processing]
    CC: debenu
    CC: stdlib_system
    CC: stdlib_os
    CC: stdlib_winlean
    Hint:  [Link]
    Hint: operation successful (20168 lines compiled; 1.422 sec total; 
34.004MiB; Debug Build)
     [SuccessX]
    Hint: R:\pdfpage\debenu.exe  [Exec]
    No stack traceback available
    SIGSEGV: Illegal storage access. (Attempt to read from nil?)
    Error: execution of an external program failed: 'R:\pdfpage\debenu.exe '
    

I'm pretty sure the DLL was compiled using a Microsoft compiler, while Nim, of 
course, is using gcc.

Can anyone advise?