The relay might be fried, or the wiring to one of your blinkers (back ones) might be corroded or unplugged. Best bet is to trace wires and make sure they're all plugged in and free of water and corrosion. If they are then I'd check the bulbs themselves and then the relay. Seems more like a blown bulb, though.
2012 CBR250R ABS
2001 CBR600 F4i