" The URI prefix is not recognized. " When exporting from Editor

[Rana Asim]

When I try to export the contents of Editor to rtf, docx or pdf I get the following error

The URI prefix is not recognized.  Description: An unhandled exception occurred during
the execution of the current web request. Please review the stack trace
for more information about the error and where it originated in the
code.
<br><br> Exception Details: System.NotSupportedException: The URI prefix is not recognized.<br><br>Source Error: <br><br>Line 11:
Line 12:     Protected Sub ExportDocx_Click(sender As Object, e As EventArgs) Handles ExportDOCX.Click Line 13:         RadEditor1.ExportToDocx() Line 14:     End Sub
Line 15: End Class