Form content to be saved

Hi there
I have created a form in Acrobat Pro with text fields and check boxes. No problems there. But when I test it in reader (the end user will only have adobe reader) the following error message pops up:
"You cannot save a completed copy of this form to your computer."
I encountered this problem age ago when using Pro 8 and all I had to do was 'enable user rights' but this function doesnt seem to be available in Pro 9.
Can anybody help?
Thanks