Are you getting any errors when you hit the upload button? Are you seeing the "warning" icon when the upload of file fails?
If you are seeing the "warning" icon please mouseover it and you will get the error as a tooltip.
If there is no any sign of error please attach the application so we can debug it on our machines.
Also can you please confirm that the "uploads" folder is properly configured and that it exists on your stage server.
the Telerik team
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