Pokemon leaf green problem?

im trying to get an all new charmander to tansfer to my platinum. i put a female charizard (lv54) and a lv41 ditto, (dittos can produce eggs with allll pokemon if they have genders) and i put them in the daycare together (in leaf green) and the old man says they don't like each other? this never happened to me before. i always produced evees and i think my cousin reproduced a squirtle but yeah. PLEASE HELP ASAP!