Authorize Net Form Requires Phone???

Hi,
When I create a form in Authorize Net Form in S2Member I get the form OK. But when I fill in all the info in the form and submit it, it says "phone number required". It looks like the form is not creating a phone number filed???
When I create a form in Authorize Net Form in S2Member I get the form OK. But when I fill in all the info in the form and submit it, it says "phone number required". It looks like the form is not creating a phone number filed???