Problems on adding digital signature

Hi,
I'm trying to add digital signature on some pdfs but my program terminate in DPLSignFileA without warning.
I work with DebenuPDFLibraryLIB0916, MFC on Visual studio 2012.
I have no idea what is wrong.
Please help.

Here is what I did:

CString inputFileName = "C:\\Temp\\test.pdf";
    CString openPassword = "";
    CString signatureFieldName = "Signature1";
    CString outputFileName = "C:\\Temp\\Signed.pdf";
    CString pfxFileName = "C:\\Temp\\aaa.pfx";
    CString pfxPassword = "aaa";
    CString reason = "";
    CString location = "";
    CString contactInfo = "";

    CStringW strLicenseKey(LICENCEKEY_DEBENU_PDFLIB);
    int m_InstanceID = DPLCreateLibrary();
    int iResult = DPLUnlockKey(m_InstanceID, (WCHAR*)(LPCUWSTR)strLicenseKey);

    int ret = DPLSignFileA(m_InstanceID, (char*)(LPCTSTR)inputFileName,
                                        (char*)(LPCTSTR)openPassword,
                                        (char*)(LPCTSTR)signatureFieldName,
                                        (char*)(LPCTSTR)outputFileName,
                                        (char*)(LPCTSTR)pfxFileName,
                                        (char*)(LPCTSTR)pfxPassword,
                                        (char*)(LPCTSTR)reason,
                                        (char*)(LPCTSTR)location,
                                        (char*)(LPCTSTR)contactInfo);

Ingo,

Thank you for reply.
Unfortunately, the problem function terminate before returning value,
so I couldn't get the result of GetLastError().
If I set parameter pfxFileName to be empty or wrong paths,
the function ends properly and returns error value.

Hi

I tried to use DLL Edition instead of LIB Edition then it works fine.
So I guess my pdfs are not protected.

The error I got in LIB Edition is 0xC0000005: Access violation.
I guess some of my setting in my IDE are incorrect but other function works well or ...