Armitage Shanks - Syphonic toilet - stopped working?

We moved our syphonic toilet so it is no longer at 90% to the outlet through the wall. The result of this is that the outlet pipe is straight out into a feeder pipe (as before) which goes into the down pipe.
Now it will not draw the waste away, the water fro the cistern raises the water level in the bowl and slowly recedes leaving waste.
If we drop water from a bowl held 6ft up it does take the waste away. Please help