Yes also some of those flex things seem to have very deformable ends so when
one does it up it can ovalise and end up leaking. I had one on our sink like
that. Bah Humbug.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Tricky Dicky" wrote in message
...
I cannot quite picture your arrangement but if you are connecting your
flexible tap connector directly on to the isolator valve then I am not
surprised you are experiencing leakage problems. The isolator has
connections that involve the use of an olive to provide the water tight seal
the end of the thread has a chamfer on the inside to mate with an olive
whilst the very end does not have a flat surface to mate with anything
tending to be rather sharp too.

What I suspect you need is something like these:

https://www.screwfix.com/p/tesla-bra...x-2-pack/2665r

The plain end goes in your compression fitting on the isolator with an olive
off course and your tap connector on the threaded end with the rubber washer
you mentioned initially.

A link to a photo of what you have got would help

Richard