DU Web Programmers - Avant Browser/JavaScript question

[Catch22Dem]

I'm a web programmer and database developer/administrator, so I'm not a programming newbie. I have a question though. I was at work the other day, and was just doing regular work stuff. I recently downloaded AvantBrowser at work to add to my list of browsers I check my code on. I make every effort to write browser independent code. So anyway, I noticed something odd, and wondered if anyone else has seen this.

If I have a text box:
<INPUT TYPE="text"...>

And I add some simple client-side script (JS) to detect the "enter" key, like so:
onKeyUp="alert( event.keyCode )"

It will pick up every single key I press EXCEPT for the enter key (which is keyCode 13) So far, this is the ONLY browser I've seen this happen with. Has anyone else experienced this? I kinda need this little chunk of code to work.