Test step loop with java issue

Hi 

For a regression test pack, I've created a test case that loops thru a folder of texts file using the content as input on a soap call. Of of the steps in the loop is a Groovy step that calls a jar to generate a security token and timestamp.

If I don't include this step in the loop, the token & time stamp don't get refreshed, but if I do include the step, everything stops dead and I have to restart soapUI. I guess it is to do with the java part - do I only need to do e.g. the import once per test case, or is there some unload I need to do before re-executing the steps with the java import in?

Many thanks for your help