I'm trying to brute force my dvwa, so I know that username and password is correct, but I must not be doing something right (user issue).... Below is the output and command string I'm using. No matter what username and password I use, I get the same output, so I know it can not be working. Could someone please help me find what other form or string I'm missing? Thank you very much!

root@bt:~# hydra -V -l admin -p XXXXX -s 80 -f http-post-form "/dvwa/login.php:usrname=^USER^&pass=^PASS^&submit=Login: Login failed"

Hydra v6.5 (c) 2011 by van Hauser / THC and David Maciejak - use allowed only for legal purposes.
Hydra (http://www.thc.org/thc-hydra) starting at 2011-09-16 09:48:37
[DATA] 1 tasks, 1 servers, 1 login tries (l:1/p:1), ~1 tries per task
[DATA] attacking service http-post-form on port 80
[STATUS] attack finished for (waiting for children to finish)
[ATTEMPT] target - login "admin" - pass "XXXXX" - child 0 - 1 of 1
Hydra (http://www.thc.org/thc-hydra) finished at 2011-09-16 09:48:37