Injector No2 leak off pipe coming off

Hi folks, after replacing injectors on my occy, 1.6tdi and replacing leak off pipe with new, the number 2 leak off pipe keeps blowing off, I've fitted new clips (but ordering another set just in case)  had to replace this injector as first one was faulty where spring clip went. New injector spring clip slot is ok.  Any thoughts as its starting to get my nerves lol