How to fit radiator vales to 8mm pipe?

I have 8mm microbore pipe that is currently connected to the old radiator valves.

I'm trying to fit the following TRV/valve;
http://www.screwfix.com/p/danfoss-ras-c-white-chrome-trv-lockshield-8-10mm-angled/53183

The old valve is currently connect as follows from the top - Valve>Olive>Nut

I understand that the Danfoss has the 8mm adapter which replaces an olive, but I just cannot work out how this securely fits to the 8mm pipe as the nut is much bigger than the old valve so I can't seem to get it to lock to the pipe when I tighten Valve>Adapter>Nut.

I've attached a picture to show the difference between the current (old) valve & the Danfoss.

How do I connect this to the 8mm pipe? Am I missing something, or have I bought the wrong valve in the first place?

Any help would be great.

Thanks,

 

Thanks for the reply.

Should the 8mm reducer be able to slide up and down the pipe? Or is it supposed to just sit at the top like in the attached photo? (It doesn't move any further down).

Thanks,

 

Ok, I'll have another go at it in the morning.

Thanks for the advice - much appreciated!

Cheers,