Some snakes prefer different foods.
I have a 1700 gram GHI that will only take mice. She will not touch a rat. So dont be fooled into thinking that just because she is big enough to eat a rat that she will, if she will not, try something else. Large mice or ASF's eventualy wou will find something she will eat
Also if she is not happy with her enclosure she may not eat or over stressed, too hot or too cold. There are many reasons a snake will not eat, you just need to find out why. is it enviormental or does she prefer a different prey? is she stressed?