Headlight problem

[Shuggie]

The driver's side headlight isn't working on dipped beam - full is OK and the passenger's side works fine. V Reg 4.0l Chimarea. Had some of the lads at work have a look at it, changed the bulb and checked the fuse box, everything OK except it still doesn't work! Bulb didn't have the rubber cap on as the manual says it should (and haven't a copy of the Bible to check) and there was no sealant on the wheel arch. Presume this is a wiring problem and am taking it into the workshop in the morning. Should be covered by the warranty (bought it 2nd hand 2 months ago), especially as just had the lens replaced as it cracked whilst pootling along the M40 to the Motorshow a few weeks back. Any advice from the wise and learned?