Single Mass to Dual Mass Flywheel Conversion Mk6 - no clutch pressure?

Hey Guys, hoping one of you helpful people could help me out with a problem i'm having...

I have a 06 2.3 petrol VJ Transit van (RWD with external clutch slave).

I have just converted the old Dual Mass flywheel to a single mass and am now getting no pressure in my clutch (the clutch is not separating from the flywheel)... At first I thought either the master or slave cylinders had gone, so I have replaced them and bled the system, but still no pressure.... I have tested the hydraulic system by applying pressure to the end of the slave, which gave me some clutch pressure, so I now know that the fault is not in the hydraulic system... When installing the single mass FW, I noticed it was considerably skinnier than the dual mass... I called the place I bought it from at the time of putting the gear box bak on and asked if I had to put any spacers or anything in there to accommodate for the difference in size, but they said, no it just all pulls together.

Now the only thing I can think of which could be causing the lack of pressure in the clutch is that the arm on the slave cylinder is sitting too far away from the clutch/pressure plate, so there is no force pushing back on it to give pressure....

So my question is, do you have to use a different slave cylinder with a longer arm on it or something in order to make it work? Or can anybody think of any other reason why this may be happening? Maybe something I may have done wrong

The strangest thing is, that when I first put it back together, we only put half the slave back in by mistake (the arm and gator had fallen off) and it worked! Not too smoothly, the bitting point was really low and pressure pretty low, but it changed gear and drove pretty fine! :-/ Then we realised, put the arm back in and it didn't work!

Thanks in advance for any help!

Cheers,

Kyle