New to the site and i have a problem with a oil leak from the rocker cover.

The car is a 2005 2liter turbo diesel with 143bhp and just over 100k on the clocks. I bought a new rubber gasket and fitted it with a small amount of RVT sealer but it still leaked oil into the timing belt cover so its now been off and on 5 times and i have tried fitting it dry and then with loads of glue but still leaking So how do they fit them and what glue is best to use to stop this leak ? I have a new timing belt to go on it but i wont fit that till the leak is sorted otherwise its only going to get covered again


Thanks for any imput on this matter