Cannot modify image title as authenticated user

Hello,

we are using the 5.x - version of acidfree on our site and currently we are trying to make per-user picture gallerys
Nearly everything works fine, the authenticated user can create albums and upload pictures.
But there is one thing that we weren't able to fix:
The authenticated user is not able to change the title of his pictures.
If he goes to the "Album content" tab and enter a different name of one image and then save the changes,
drupal will say "The changes have been saved" but the image title is still the same as it had been before
This is very strange, as an Administrator is able to change the title of images.
We've given the authenticated user access to all features of acidfree, images and image upload but the problem still exist.

So we are not sure, if this is a problem with access management or a bug in acid free
Btw: If it is a problem with access management, please tell us, what access a user need to have to change the title of images

with kind regards,
the webteam of Aichfeldjugend - www.aichfeldjugend.at