Check the fuse. AC output goes from the stator to the rectifier/regulator then from the RR to the main fuse then to the battery.
Ok if its not the fuse remove your seat and unplug the rectifier/regulator. You should have continuity between all the white stator wires (not sure exactly what the resistance is but they should all be close to each other) and no continuity to ground on the white wires. You can go one step farther to check the stator by firing up the bike and checking for AC voltage also between all the white wires (I think ~ 50 volts AC). If your bike passed that test plug the RR back in fire it up and check for 14 volts DC coming out of the red wire. If no replace the RR. If yes check wiriing to fuse then to battery. hope this helps.