Any doctype will do the job and keep browsers standard. It's an issue though, using a transitional doctype, because you are essentially telling the browser that your page is in transition mode from years and years ago. And unless you are serving a mime type for text/xhtml, you aren't using TRUE XHTML, more like fake XHTML. If you were to be using XHTML, and serving the mime type, IE wouldn't be playing along and even showing the website.
You should really be using a HTML4.01 Strict doctype (for the reasons in the above paragraph).
As Ralph said, it won't FIX your problems, but changing your doctype (although a few validation errors may go away/come due to the change).
Are you viewing the page in dreamweaver? Or I assume online on a web browser. Is it different browsers not displaying hte button?