There is missing dll from your bin folder which is used somewhere or it is referenced by an existing dll. Currently the application is trying to find it and you get this error. Please check whether you have all dlls in your bin folder.
All the best,
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items