Hello Shathish Kumar,var slidingZone = $find("<%= RadslidingZone1.ClientId %>");
may return null value for the slidingZone if RadSlidingZone1 has not been rendered on the page. For example, if you execute this script before RadSlidingZone has been loaded.
One thing I noticed in the line var slidingZone = $find("<%= RadslidingZone1.ClientId %>");
is the letter 's'
being in lower case. Does the sliding zone at the page have 'RadslidingZone1'
Would you please check how you have registered the script which expands the sliding pane when a post back event occurs? You need to use Sys.Application.add_load(expandSlidingPane);
when registering the script as it is shown in the ExpandedSlidingPaneOnPostBack.aspx.cs
page. When testing the page I had sent you do you experience the problem slidingZone having a null value or you experience it only with your own project?
In case you are not able to find the reason for experiencing the problem by yourself, please, send me your application and I will do my best to help you.
the Telerik team