Thank you for contacting us.
Do you mean you have opened the demo online or you have downloaded the source and run it locally? On which view do you experience this issue? If you run this locally, can you please make sure the connection string in web.config file points to the right SQL express and the .mdf and .ldf database files are with ReadOnly attributes set to false?
Let us know if the problem persists.
the Telerik team
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