Forms appear differently in Acrobat and in Adobe Reader

I created a form in Livecycle 8.2, then distributed it using Acrobat Pro 9. Then something weird happens: When I open the distributed form using Acrobat 9, the "submit form" button appears on the purple bar across the top of the PDF. But when I open the same distributed form in Adobe Reader, the "submit form" button appears as a drab gray button on the upper right corner of the form itself -- even though the purple bar is there, it only shows the "highlight fields" button, but not the "submit form" button. I'm afraid that my users who use Adobe Reader will miss the "submit form" button altogether. How can I ensure that the "submit form" button appears in the purple bar when the form is opened in Adobe Reader? Thanks.