Hi Sanjay,
Did u able to resolve this issue, as i am getting same exception.
I am using RadGrid with RadTabStrip inside nested Detail.
Message: Invalid JSON primitive: .
Stack Trace: at System.Web.Script.Serialization.JavaScriptObjectDeserializer.DeserializePrimitiveObject()
at System.Web.Script.Serialization.JavaScriptObjectDeserializer.DeserializeInternal(Int32 depth)
at System.Web.Script.Serialization.JavaScriptObjectDeserializer.BasicDeserialize(String input, Int32 depthLimit, JavaScriptSerializer serializer)
at System.Web.Script.Serialization.JavaScriptSerializer.Deserialize(JavaScriptSerializer serializer, String input, Type type, Int32 depthLimit)
at Telerik.Web.UI.RadWebControl.LoadPostData(String postDataKey, NameValueCollection postCollection)
at Telerik.Web.UI.RadInputControl.LoadPostData(String postDataKey, NameValueCollection postCollection)
at System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)