Hydra failure string Problem

I am trying to hack myself (searching for my login form vulnerabilities). So I'm trying Hydra for the first time and I used this command:

hydra -L user.txt -P pass.txt -s 8080 "my ip" "username=^USER^&passsword=^PASS^":"Wrong"

But it didn't work because of the failure string... Because I changed it to a string from the success page and it's still the same thing.

Sometimes it gives me that all the entries are correct and other times it gives that none is correct.

I need help please...