Program can't find toolbox classes on the iSeries

I'm trying to run a simple java program containing jt400.jar access classes on 
the iSeries.

I have the jt400.jar, the jt400ntv.jar, and the jt400Native.jar files in the 
/QIBM/ProdData/Java400 directory. I have also tried with just one these jar 
files in the directory. 

I used WRKENVVAR to set the CLASSPATH enviornmental variable to each of the 
following:

'.:/QIBM/ProdData/Java400/jt400.jar'
'/QIBM/ProdData/Java400/jt400.jar'
'.:/QIBM/ProdData/Java400/jt400ntv.jar'
'/QIBM/ProdData/Java400/jt400ntv.jar'
'.:/QIBM/ProdData/Java400/jt400Native.jar'
'/QIBM/ProdData/Java400/jt400Native.jar'

I have also tried these same classpaths as parameters in the JAVA command from 
the command line.

No matter what I do, I get an error saying: 

        java.lang.NoClassDefFoundError: com/ibm/as400/access/AS400              
     
        at java.lang.Throwable.<init>(Throwable.java:195)                    
        at java.lang.Error.<init>(Error.java:49)                             
        at java.lang.NoClassDefFoundError.<init>(NoClassDefFoundError.java:40)  
                                                                          
        at ExtolCl.callProgram(ExtolCl.java:9)                               
        at ExtolCl.main(ExtolCl.java:29)                                     
        Java program completed with exit code 1                                 
     

It's finding and executing the class I wrote (ExtolCl), which is also in the 
/QIBM/ProdData/Java400 directory. It doesn't seem to be able to find the 
toolbox classes. 

What am I missing??? Here's the source code for the program, if that helps:

import com.ibm.as400.access.*; 
public class ExtolCl {
 public String errorParm = "";
 public void callProgram() {
  try {
    AS400 system = new AS400("mysystem", "myname", "mypassword");
    ProgramCall pgm = new ProgramCall(system);
    String program = "/QSYS.LIB/EXTOL.LIB/EXTOLCL.PGM";
    ProgramParameter[] parameterList = new ProgramParameter[1];       
    parameterList[0] = new ProgramParameter(1);
    pgm.setProgram(program, parameterList);
    if (pgm.run() != true) {
      errorParm = "1";
    } else {
      AS400Text errorValue = new AS400Text(1);
      errorParm = 
(errorValue.toObject(parameterList[0].getOutputData())).toString();
    }//end-if                   
    system.disconnectAllServices();
  } catch (Exception e) {
    errorParm = "1";
  }//end-try-catch
 }//end-callProgram
 public static void main(String[] args){
  ExtolCl test = new ExtolCl();
  test.callProgram();   
 }//end-Main
}//end-ExtolCl
 
Thanks in advance for any help!

Kelly