Hey, I am installing a new shower tray. However am having problems with the waste. The thread that goes through the tray and screws to the trap below is not long enough to start threading with both washers on ( top and bottom) niether will it start threading with just one of the washers on. It will only start threading to the trap with no washers on beacuse off the depth off the tray. Would silicone both sides make a leak free joint. Or do the sel traps for shower trays that have more thread on. Has anyone else had this problem.