I am really new to ubuntu (12.04) to automount my drive I added this line to fstab

/dev/sda4 /media/FF15-ED92 vfat defaults 0 0

But now when I want to delete a directory or a file it doesn't delete like using del key of keyboard so right clicked on that directories and files but there was no option to delete and move to trash was also not clickable. So how can I give myself permissions to do this. Also I can't do this on my pen drive also.

I tried this but nothing happened

sudo chmod 777 /media/44gb

if I change from chmod to chown then it gives that

changing ownership of `/media/44gb': Operation not permitted