problem fitting a new Wirquin jollyflush?

Hi,
Fitted this into my cistern. Diagrams suggest that the white "grip" on the flush mechanism should be near the bottom of the central "tube" , however it will only fit near the top.
Having fitted it all I find that the push button does not work it just loosely goes down without any affect. Do you think there might be a spring missing or could it be that the cable is somehow in the wrong place please?