Modul contenttype category

When I save a Modul with contenttype "category" it swiches to contenttype "product" after saving

Any suggestions?

Joomla 2.51

It must be a problem with the save.

Please try to activate the debug mode of the configuration of Joomla and try again. If you get an error message please report it to us. Otherwise, turn it off again and try with another browser, that might help.

I had 2 test categories and only one test product.
After installing a few more products the Problem disappeared!