Try opening the file again in Acrobat (full version, not Reader) and check in for something like Enable for Acrobat Reader in the Tools or Advanced menu. Check that and then resave. This needs to be done for it to work in Reader.
Thank you Larry. In Acrobat X you go to Save As and there is a Reader Extended PDF/Enable Addition Features which will enable Submit Form to work.
I changed the Submit Form box to Email Form.
However, when I sent it to a friend who uses a Mac but uses gmail online he says:
In Adobe Reader, when I fill it out and click Email Form, nothing happens.
When I try to save it, I get this dialog informing me that the data I entered will not be saved.
I can print the thing, but Adobe overrides the built-in print dialog from the Mac, so I cannot print to PDF.
Did you reenable the file after changing the Submit to Email? this sounds like enough of a change that reenabling might be necessary. Can you post a link to the file for others to try?