I've put a new water inlet thing in the toilet, which seems to work Ok, but is a bit noisy but now it leaks from the connection of the water inlet pipe that sticks out of the bottom of the cistern and the copper water pipe, i've undone the connection nd looked to see if any bit of grit or dust is in it but its clean and then re connected it and tighened it. Do i need to buy something to stop it leaking or have i done something wrong?