C# call Javascript at folder level and get "value does not fall within the expected range"

I want to convert PDF to postscript. After doing some research, I wrote the following code but got the exception mentioned in title.

AcroPDDoc acroPDDoc = new AcroPDDoc();

var rc3 = acroPDDoc.Open(source);

var jso = acroPDDoc.GetJSObject();

var what = jso.PDF2PS();

acroPDDoc.Close();

Javascript in c:\program files (x86)\adobe\adobat 2015\acrobat\Javascripts. I commented the real code and only returned a value but still got the above exception.  Please help. I am in a rush to deliver this piece of code. Thank you very much. J

function PDF2PS()

{

  //var pp = this.getPrintParams();

  //pp.fileName = filename;

  //pp.printerName = "";

  //this.print(pp);

return 12345;

}