Soot API: VerifyError when using Chain.insertBefore() methods

[nathan gulley <ngulley@juno.com>]

Hello,

I am trying to use the following routine along with the Soot API to
insert code before every return statement 
in a method called "v on class called "test.LoadMe".

                  JimpleBody body =
(JimpleBody)sootMethod.retrieveActiveBody();
                  Chain units = body.getUnits();
                   String methodStr = "<test.LoadMe: java.lang.String
v(java.lang.String, java.io.InputStream,  
                                                       java.util.Date)>";
 
                  SootMethod method = scene.getMethod(methodStr );
                   ArrayList params = new ArrayList();

                  // add method parameters to params
                  .
                  .
                  .

                  Unit postCondMthdUnit = Jimple.v().newInvokeStmt
                        (Jimple.v().newStaticInvokeExpr(method ,
params));

                   Iterator unitIterator = units.snapshotIterator();
                  
                    while (unitIterator.hasNext()) {
                        Unit nextUnit = (Unit)unitIterator.next();
                        if (nextUnit instanceof JReturnVoidStmt ||
nextUnit instanceof JReturnStmt) {
                              units.insertBefore(postCondMthdUnit,
nextUnit);
                        } 
                    }


However, I recieve the following a Verify Error when executing the class.


          Exception in thread "main" java.lang.VerifyError: (class:
test/LoadMe, method: v
          signature:
(Ljava/lang/String;Ljava/io/InputStream;Lcom/rtscinc/util/DebugMsg;)
          Ljava/lang/String;) Incompatible argument to function.

I would appreciate any advice on what may be the cause of this problem. 
I have attatched the Jimple
code for this instrumented class also. 

Nathan

test.LoadMe.jimple