pcml problem

[web3user]

I tried to run a java program to test pcml, but ran into an error:
java.lang.NullPointerException
at com.ibm.as400.data.ProgramCallDocument.setSystem(ProgramCallDocument.java:825)
at qsyrusri.main(qsyrusri.java:44)
The error points to line 44:

AS400 as400System;
ProgramCallDocument pcml;
as400System = new AS400("prod", "myuserid", "mypasscode");
pcml = new ProgramCallDocument();
pcml.setSystem(as400System); // line 44
pcml.setDocument("qsyrusri");

The object as400System was successfully created. But I always got the error when I tried to call pcml method "setSystem".

Any suggestions are greatly apprecited.

Thanks.