I'm wanting to redirect the "Print Labels" button on an Item Reciept, I've done the same sort of thing before and understand about using nlapiSetRedirectURL and form.setScript, this is not my problem.

The User Event Script is set against the Before Load Function and correctly referenced in the Script.

I've used the debugger and can step through the code when the page loads.
The first check I make is if the type == 'print'.
On Page Load the 'type' is of course "view". (no use to me except to prove the code is run and can be debugged).

OK so, when I click on the "Print Labels" button the script never fires, I never have the opportunity to debug the code, this kind of makes sense since the page has loaded at this point and I suspect the page is not reloaded when you click the Print Labels button.