Breeding don't work

[LUC1G07CH1]

I tried to breed 2 pets on my site but the site says that my pets belongs to an unbreedable species. But...all species are breedable!

And how we choose images to the cubs?

And something like this?
Default pet x Default pet=Default Pet
Default pet x Other pet=Color/mutation combo
Other pet x Other pet=Color/mutation combo
Same pet x Same pet=Same pet

I just cannot understand the things...

Edit: I tried to breed 2 different pets,but it just comes out like the default breeding setting. How we fix that?
Another edit: Nevermind,i need to put the female and male pets for breeding,and then,invert the form. Easy but takes awile.