RadControls for ASP.NET AJAX
Compatibility issues with RadScriptManager and RadStyleSheetManager
Because the page does not go through its normal life cycle, after the RadControls have been updated by the RadXmlHttpPanel, the controls’ scripts and stylesheets need to be evaluated and applied, respectively. This, however cannot be done if the scripts (and the stylesheets) are combined into a single file - the RadXmlHttpPanel cannot find the right scripts and styles for the respective RadControl. That is why there might be client-script errors and the styles will not be applied correctly if the RadXmlHttpPanel is used together with the RadStyleSheetManager and the RadScriptManager.
There are 2 ways to solve this problem:
use the Microsoft AJAX ScriptManager control
set EnableScriptCombine="false" for RadScriptManager and EnableStyleSheetCombine="false" to RadStyleSheetManager.
Event Handlers Might Not Be Not Raised in a Default Document in IIS 7 or IIS 7.5 Integrated Mode
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 RadXmlHttpPanel.
This problem is caused by a breaking change in .NET 4.0 described here. 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).