But are you certain you put the runners in the right way round?
The deep one goes at the top.
Sorry if this doesn't apply as I haven't seen the type of cage you are discussing but I have picked up the wrong piece of runner in the past myself.
dr del
that is very true, I haven't seen these particular cages myself either but I know that my AP cages are like that (it's what allows you to easily remove the glass)