We recently upgraded Telerik Dlls from 2011 to 2013, 
We are facing some issue
1: We are receiving compilation error The 'ClientCallBackFunction' property cannot be set declaratively.

Code snippet is like 

<telerik:RadWindowManager Visible="true" Modal="true" Behavior="Close,Move" OffsetElementID="OffsetElement"
            ID="RWindow" runat="server" ClientCallBackFunction="ClientCallBackFunction" KeepInScreenBounds="true"
            ReloadOnShow="true">

-------
  <telerik:RadCodeBlock>
   <script type="text/javascript">
                function ClientCallBackFunction(sender, eventArgs) {
                    if (eventArgs == ‘close it’) {
                        window.location.href = 'Somepage.aspx';
                    }
                }
            </script>
        </telerik:RadCodeBlock>

2:  In RadGrid’s OnItemCommand event  code snippet e.Item.Cells[0..to n].Text always returns &nbsp;. 

Problem is this is live site and we need to fix these as soon as possible, looking forward for your response.