A page can have only one server-side Form tag error message when i try and use a web user control in my master page

 I have a master page that basically has the header and some drop down menus. I have a web user control
that consists of a hyperlink labeled "Sign Out" so if the user clicks on it, they are signed out of the
application. The problem I am having is that if I drag and drop my user control anywhere on my master page I
get an error message. (A page can have only one server-side Form tag.)
Can anyone tell me what the problem is and if it can be fixed?
<%@ Master Language="C#" AutoEventWireup="true" CodeFile="Student2.master.cs" Inherits="Student_Layout_ver2.Student2" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" > ...