Give it a gentle whack and see if it starts working. (No, really) Most of the time it will, which will tend to indicate that you need to yank the bulb, clean the contacts inside, and protect with a nice dialectric grease. My 2008 Vulcan does this from time to time, and those contacts in there build up a residue/corrosion that stops the flow.
I used a battery terminal brush in mine, GENTLY, without the grease the 1st time, and it kept it good for over a year. After that, a brush and the grease and I haven't had a problem since.
BACA Pretzel - Flyin' the highways in OK!
'08 Vulcan 1600 Nomad - "Grace"
Metallic Diablo Black/Candy Fire Red
Vance and Hines Duals
Kuryakyn Flame grips with Throttle Boss and Stiletto endcaps
Kuryakyn Longhorn offset highway pegs
Vista throttle lock
OEM light bar and luggage rack
B.A.C.A. Member, Oklahoma Chapter
Out to pasture - 2008 Vulcan 900 Custom: Redemption