How to reference

Hi, I try to sign PDF document with my certificate file. I used code from SDK:

AcroAVDoc g_AVDoc = null;

string pdf = @"C:\Users\myprofile\Desktop\tests\1.pdf";

string pfx = @"C:\Users\myprofile\Desktop\tests\cert.pfx";

string pwd = @"mypwd";

g_AVDoc = new AcroAVDoc();

g_AVDoc.Open(pdf, System.IO.Path.GetRandomFileName());

if (pdf != null && g_AVDoc.IsValid())

{

   CAcroPDDoc pdDoc = (CAcroPDDoc)g_AVDoc.GetPDDoc();

   object jso = pdDoc.GetJSObject();

   object[] param = new object[1];

   param[0] = pwd;

   object con = jso.GetType().InvokeMember("SetUserPassword", BindingFlags.InvokeMethod, null, jso, param);

   param[0] = pfx;

   con = jso.GetType().InvokeMember("SetUserDigitalIDPath", BindingFlags.InvokeMethod, null, jso, param);

   param[0] = jso;

   con = jso.GetType().InvokeMember("AddSignature", BindingFlags.InvokeMethod, null, jso, param);

}

but I got an error "Unknown name. (Exception from HRESULT: 0x80020006 (DISP_E_UNKNOWNNAME))" on line "object con = jso.GetType().InvokeMember("SetUserPassword", BindingFlags.InvokeMethod, null, jso, param);"

I think, the code cannot find a javascript method "SetUserPassword", but I don't know how to provide the file path or how to reference it (I have referenced Adobe Acrobat 9.0 Type Library). Can you help me, please?