Allowed Filetypes - no .jpg, gif etc

Hello,
I know that there is an issue opened regarding not allowed filetypes (http://drupal.org/node/1505108) but I'm using the dev version.
Using the filedepot page (/filedepot) as an admin I'm not allowed to upload .jpg, png or .gif files.
I click on the "New file" link and the popup opens. I choose the file to upload and click the upload button to the right of the text field. At he bottom of the popup I then click "Upload File". Then I recieve an error message that this file type is not allowed.
When I click on the filename another popup opens with an error message:
The requested URL "/system/temporary/filename.png" was not found on this server.

When I click on the "File remove button" next to the file I would like to upload nothing happens. The actity indicator appears and dissapears. So I can not choose another file but have to close the popup and start over. There are no Java Script errors.

The filestypes are all listed on the filedepot settings page as allowed filetypes.

Following the example in the thread (http://drupal.org/node/1505108) I went to the following page:
/admin/structure/types/manage/filedepot-folder/fields/filedepot_folder_file
and added jpg, gif, png. But this did not solve the issue for me.

However if I edit the folder via the node edit form I am allowed to upload jpgs and so on. But I am not allowed to download them when I use the /filedepot page. I get an acces denied error altough I am listed a the uploader/owner of that file.

Thanks
cat