In the HTML you posted no where you are closing
asp:ContentPlaceHolder
Also
ajax:toolkitscriptmanager is closed outsite the html tag. this is not the proper way. It should be declared like given below -
<ajax:toolkitscriptmanager xmlns:ajax="#unknown"></ajax:toolkitscriptmanager>
Additional ajax toolkit scriptmanager is declared which .net will not allow.
Clear all the issues and try to run the page again