Also do you have the document which briefly describes the INVERSE function. I sometimes get the ERRORCODE output from INVERSE function as nonzero, which means the inverse function could not find possible solution. I had emailed the KUKA service asking for this document, but had no luck to receive reply on the same.
Doing a quick search for inverse() or forward() will turn up an old KSS feature request outline for forward and inverse functions. It's poorly translation into English but it's better than nothing. Still I would appreciate up-to-date English documentation on the functions as I'm having similar issues in my application. I've also asked Kuka for this recently -- to no avail. Apparently more current documentation exists in German. "E_KRL-command for Transformation_20" I think is the attachment you're looking for.