[gentoo-user] usb stick files read only

[Joseph]

I've a usbstick formated with ext2 file system and must have use it on a different computer because when mount the usb stick I get file ownership:
-rw-r--r-- 1 test   users     692926 Jan  7  2012 asterisk_1_4_39.tar.gz
-rw-r--r-- 1 test   users       8502 Jul 21  2011 asterisk-help.txt
-rw-r--r-- 1 joseph  1000      22696 Mar 26 18:27 asus_10-0-0-1_shaw_nvrambak.bin
-rw-r--r-- 1 joseph  1000      22459 Mar 26 16:16 asus_home_10-10-0-1.nvrambak.bin

The ownership should be joseph:users but when I try to change (as root) it I get : Read-only file system
chown -R joseph:users /media/stick/*
chown: changing ownership of `/media/stick/asterisk_1_4_39.tar.gz': Read-only file system
chown: changing ownership of `/media/stick/asterisk-help.txt': Read-only file system

How to deal with it?
I the past changing the ownership always worked from root.

-- 
Joseph