Problem in text based terminal when logging as root
 

i'm using suse 9.3,when i logged in to my text based terminal and when i asked for root access by su command and typing my password i get an error message telling me that password is not correct.,
on the other hand,when i log into konsol in x-window everything gonna be ok and i can log in as root by using my current password.
i tried to change my password but everything still as it is.

Does your password contain non-english letters?

no,it's in english