Hmm. You should have this equation:
You can see that there is only an multiplying C, not a
Carry this correction all the way through to see how that changes things.
You should have
You'll see that there should be an s in a coupled of places, not a 2. Also, no need to multiply by Cs+D top and bottom, since that's in the numerator, and plays no role in determining the common denominator.
What did you get for A and B?