Trying to connect new chrome effect 15mm pipe to new cistern. Bought a C x Fi coupling 15mm x 1/2"(42832-92) from Screwfix as this seemed to be only chrome fitting available but, unlike a conventional tap connector it doesn't have a spigot inside it. Will this connect to the plastic male thread on the cistern (with fibre washer) or will it leak? If the latter, what should I use instead?