Let's break this down to the basics of what a punnet square actually is. When dealing just one trait, the square is two by two. The letters across the top are the possible genes that one parent can pass on, and the letters down the side are for the other parent. Since your only dealing with one trait (two genes) there are only two possibilities (i.e. a het albino can pass on the normal gene, or the albino gene, but not both). It is the same thing with two traits, except the square is four by four. The two traits have nothing to do with each other, and are inherited independant of each other, so there are four possible combinations of genes that can be passed on by each parent. An albino bred to an axanthic would produce ALL double hets, meaning all the offspring would be carriers of both traits, but would look normal since wild-type is donimant over both traits. So if aaXX is an albino, and AAxx is an axanthic, all the offspring would be AaXx. aaXX can only pass on aX, and AAxx can only pass on Ax, so the result can only be AaXx.

-Evan