headlight problem ?

hi there
I have a new Roadster 2012 model . over the weekend I installed decent air horn using relay etc ,works great but originally didn't as I wired relay wrong and blew fuse that horn,indicators are linked to somehow
I have only had bike 10 days and today I noticed that headlights not on!?Might never have worked but seems too much of a coincidence
I thought that fuse has blown but it hasn't and I have checked all fuses with a meter
The bike had accessory heated grips fitted and they don't appear to be working either. I can't find reference on the Triumph site relating to a fuse that perhaps I've missed?
everything else works
the bike is booked in for 500 mile service on 5April and I can get dealer to look at it but still think I must be missing something obvious!
any ideas gratefully received
Cheers
Mal
Chester UK

Start it in neutral with the kickstand down. Pull in the clutch & put it in gear to see if your kickstand safety switch is working. If not, then check fuse #10. You might as well double check 2 & 9 while your at it. I prefer to leave the fuses in place and check for voltage across the fuse holder assembly with everything powered on in case of an open circuit not related to the fuse itself. Set your meter on Vdc and read across your battery to verify the meter is working and you've got the right settings. Then find the nearest points to check across the fuse (outside of the fuse holder). zero volts is good......12 volts and you've found your problem.
BTW: Where did you tie in the horn relay?