Could Not Generate XML File. Please try again

hey, I installed your tool on my page. thanks for this great tool I'm just having one problem. On the Masterpage i can't add any sites. It always shows me following error message when i try to save my page.
Could Not Generate XML File. Please try again

If the component needs to create some file, the file persmission might be the solution. but i don't know if it is suppose to create any.


Thank you

Edit: The file permission is set correct, is does not cause the issue!