Add write permission to ftp folder

Question

I can't figure out why, if I'm in group ftp and data folder has write permission to group, I can't create a new file in it:

neurino@sensor:~/ftp$ id neurino
uid=1000(neurino) gid=1000(neurino) groups=1000(neurino),115(ftp)
neurino@sensor:~/ftp$ ls -l
total 168
drwxrwxr-x 2 ftp     ftp     73728 2011-09-26 14:54 data
neurino@sensor:~/ftp$ touch data/file
touch: cannot touch `data/file': Permission denied

Any advice?

Answer 1

I searched in the wrong place, here's the answer: I have to log out and back in:

http://unix.stackexchange.com/questions/6387/how-to-add-write-permissions-for-a-group