It misses the AjaxControlToolkit.dll in the bin directory after you deploy the site.
Solution:
1. Get AjaxControlToolkit via http://ajaxcontroltoolkit.codeplex.com/releases/view/43475
2. Add AjaxControlToolkit.dll to your Reference folder(Right Click on Reference Folder > Add Reference > browse AjaxControlToolkit.dll).
3. Set Copy Local to True
4. Publish your site.
Article ID: 1475, Created: August 18, 2013 at 10:54 PM, Modified: August 18, 2013 at 10:54 PM