Hi Marhaban,
You know some of the submission rules have changed on Cucumis during this year.
Rule [4] says that isolated words are no longer accepted for translation.
I think it is the case of this translation.
Please, next time you see a request like this call for an admin instead of doing the translation OK? Have a look at the other 8 rules in case you haven't yet.
We don't want our users to think that experts have privileges.