Sidelight issue - help!

[Assa1974]

The front passenger side sidelight is not working on my Blobeye despite me changng the bulb (the old one did look like it had blown). I assume as the drivers side is working fine it can't be the fuse so am I right in thinking it's a wiring issue? Any advice would be greatly appreciated as I'd like to sort this myself rather than have the garage do it when they MOT the car next month. All other lights, front and back, are working.