Help! My ignition is dead!

Rotax 912ULS, 800hrs, built 2005

The plane has been flying perfectly for 12-ish hours since last 100hrs.maintenance.

One week ago, pulled it out to fly.... and it will not start. Not a cough, not a splutter, just nothing.

The battery is new and fully charged, and the engine cranks normally. Compressions are good. Fuel pressure is good, carbs are clean.

Given the multiple redundancies in the ignition system, I can not understand why it will not give at least a cough on one cylinder! So, plugs out, all are damp with fuel as one would expect after a failed start, but correctly gapped and good colour, all look the same.

To me, the obvious likely fault: Checked for short-circuit in the mag switch and wiring, etc. - no defects found.

So cranked the engine with plugs out (in case of accidental start!!!) to check for sparks. No spark on any cylinder.

Checked for correct grounding of all ignition parts to engine and airframe: no defects.

I cannot think of any one faulty component could cause such a problem : there is redundancy built in to everything! and I am reluctant to accept that several elements could have failed simultaneously when it was perfect last week and nothing has been done to affect it since.

Does anyone have any useful insight?