Hi Kerri,
Sounds like it's defective to me. After I came home from finishing my rad treatment, I was using my peg for o/night feeds and additional fortisip/ensure drinks but the cap and assembly underneath it came off, so I had a minor panic for 5 mins but luckily my son was here and looked in the supply box I'd been sent home with and there was a whole spare part in there that I'd never noticed and together we managed to change it. No problems since with that, so have you got any supplies like this perhaps? My peg line has a clamp on it, hasn't yours?
Anyway, hoping it's sorted for you soon.
Take care
Lynne