I checked your exercise. There were a few mistakes. It seems that you had forgotten to raise the 7th in the III+ and V chords of the minor scales. The 7th scale degree must be raised in those chords in order to have the appropriate properties. For example, in G minor your III+ chord consisted of Bb-D-F (A major triad). But in the Harmonic minor III+ is an augmented chord. The augmented property comes from the raising of the 7th scale degree in the chord. Therefore, in G minor your III+ chord should be:
Bb-D-F# Remember that an augmented triad requires to Major 3rds stacked on on top of the other. Bb-D (Major 3rd #1), D-F#(Major 3rd #2).
I've attached the exercise pointing out where you left our the raised 7th degrees in various chords.
Make sense? You also had the same problem with you V chords.
By the way, your Db chords were fine. Of course you would need the B double flat in the key signature as well.
I would like for you to do another exercise so for a little more practice. This time the keys are: C minor, Eb minor, A minor, F# minor. This exercise will also be in Harmonic minor. Don't forget to raise your 7th scale degrees at all times!
