extreme giant x b&w

[White_Lotus]

I'm wonderin why it hasnt happened =S I'm not so read-up or educated on breeding but is it because female Extreme are the same size as male argentines and female b&ws are to small for male extreme giants? Are compatible? I have a male b&w and a female extreme giant. I've had to separate them recently because my male Akira is chasing Bella around like a freakin horndog lol