Harness Training, is this normal?

[Becky]

So little Bungo is currently wearing a H style cat harness, and has appeared to have forgotten how to walk! He isn't meowing or showing any signs of distress but he has been rolling around and crawling on his belly since we put it on him. We put him on his feet to walk and he just falls to the floor. Is this normal?? Or shall I take it off him? Like I say, he doesn't seem bothered just a bit confused by it all, almost like he's drunk!