[sqwebmail] deleting folder content

[J.M.Roth]

Hello,
I can't seem to do the obvious thing: deleting the trash contents.
I click on the radio button next to Trash then the "delete folder 
contents" checkbox then on "Delete Folder".
The result always is : "Unable to delete or rename this folder - folder 
contains messages or is used by a mail filter"
This simply is not the case.
Same thing for every other folder btw.
Best regards
-jm