Scale I used is Bb natural minor,not harmonic minor,
harmonic minor has # 7th which isn't the case here.
Ohh,and harmonic minor surely ISN'T greatest solution for the blues.
You should stick to minor pentatonic and blues scale
(same as minor pentatonic with chromatic note between 4th and 5th) to get bluesy sound.
Hope this helps,let me know if you need more info.