"The pizza has cheese and tomato."
Translation:Η πίτσα έχει τυρί και τομάτα.
Because you forgot to translate "The pizza has cheese and" :)
More seriously, please ask about complete sentences -- it's possible that one word is correct in one sentence but not in another or that it only works in some variations.
I've checked the incubator just now and "Η πίτσα έχει τυρί και ντομάτα." is accepted.