Xray button does not work when I append an object

When I append a set of teeth to put in my character mouth, my x-ray to see the bones seem not to work, I see the bones inside the body through the open eye holes, but they do not show show through the body, instead my teeth seem to disapear when I click on the xray button, any glues?

I think you may need to post a blend file. maybe you had both selected teeth and bones. look in the eye and make sure only the bone is selected. look for the objects name listed.