Hello can someone please help me here I've got a MDPE stopcock (25mm MDPE to 15mm copper) and tried every method I can think of to connect it but each time there's always a small leak it's driving me nuts I've been trying all day please someone explain there's an olive type thing on the MDPE side but it's got a small manufactured gap in it I don't get it the standard olives don't have gaps in them this has a plastic O ring but that only protects one side and the olive type thing doesn't even go over the 25mm pipe it's about a mm short all round (it only goes over the end of the pipe insert) I tried stretching it but broke one previously and had to get a whole new stopcock this is driving me nuts the plumbers I asked said they don't deal with MDPE and there were no instructions with the taps please someone help me pleeeeeeeeeeease