Event Handlers Are Not Raised
When RadCompression is enabled and you are using .NET 4.0, event handlers might not be raised in a default document in IIS 7 or IIS 7.5 Integrated Mode, which could break the normal work of RadButton.
This problem is caused by a breaking change in .NET 4.0 described in this official ASP.NET Breaking Changes section. To workaround it one can set preCondition="managedHandler" for the RadCompression module. You may also need to remove the runAllManagedModulesForAllRequests setting from your web.config if you have it (or set it to false).