I am trying to bind data to a GridView using ext.net. But I am getting the error like "Method not found: Boolean System.Runtime.Serialization.DataContractAttribute.get_IsReference()".
You may need to install .net Framework 3.5 Service pack 1. After that Reinstall ext.net.
It seems you haven't updated the Framework. Also to get quick reply I would suggest you to post this in ext.net forum as you may not find many experts in other forums.