deleted files don't want to end in the trash bin

[KRS <fogia flashmail com>]

I write here because nobody in Ubuntu forums neither in the ubuntu
mailing list can help me.


I have a raid5 volume /dev/md0, I mount it in /mnt/raid using the fstab :

/dev/md0    /mnt/raid/    ext2    defaults    0    1

In /mnt/raid/ I have a folder owned by me (me=nevada)

:/mnt/raid$ ls -all
total 28
drwxr-xr-x  4 root   root    4096 2008-10-12 14:43 .
drwxr-xr-x  3 root   root    4096 2008-05-03 11:32 ..
drwx------  2 root   root   16384 2008-10-12 14:33 lost+found
drwxr-xr-x 11 nevada nevada  4096 2008-10-14 18:30 mamoth

When I want to delete a file in mamoth/ with nautilus I get a warning 
message : (translated from the french)

"Impossible to send the file in the Trash. Would you delete it 
immediately ?"

[cancel] [ignore all] [ignore] [delete all] [delete]"

Why my files won't end in the trash? What can I do to correct this?

Thank you for your help.