executing quip from java

We are using this java function to call quip from java :

import java.util.;
import com.softwareag.xtools.quip.xqueryAPI.
import java.lang.*;

public class TestAPI {
public static void main(String [] args){
Properties prop = new Properties();
try {
prop.put(“quipcmd”,“quip.exe” );
Connection conex
= DriverManager.getConnection( “C:/QuiP/bib.xml”, prop );
QueryResult res = conex.executeQuery((String)args[0]);
}catch (XQueryException e) {
System.out.println("XQueryException: " + e.getMessage());

our xml file is bib.xml the path is c:/QuiP/bib.xml and when we execute the java function as written above we get the message :

C:\QuiP>java TestAPI quippy.xquery
Exception in thread “main” java.lang.NullPointerException
at TestAPI.main(TestAPI.java:12)

For our test I execute a very simple Xquery query ( to check if the connection works properly but It seems not to… ) :

{ document("C:/QuiP/bib.xml")//book[2]/author/la }

Its name is quippy.xquery and the path is c:/QuiP/quippy.xquery
I don’t know where to indicate the source of the xml data, and I’m not sure of what is written in red in the java function.
If somebody could help me…