[eluser]coffey[/eluser]
sorry about the delay in replying .... snowed under with work at the moment.
I couldn't see any problem with your code at all so I popped it verbatim into one of my forms and it behaved as it should.
The only thing I can think of is that as my site is under development I have been using the svn version rather than the normal download .... perhaps this is at the core?????