Find the energy stored in the 1.0µF capacitor when a 48V battery is connected between points A and B

http://session.masteringphysics.com/problemAsset/1256774/2/RW-23-54.jpg

This should be the link to the image given in the problem. I worked this problem out and ended up with 24 µJ but it is wrong for some reason. Please explain in steps how you got the answer you came too.

Relevant equations:

C = Q / V
U = (1/2)CV^2

Guidelines:
Capacitors in parallel have the same potential difference (V) between their plates.
Capacitors in series carry the same charge (Q).

V=48 V
C3= 3 uF
C2= 2 uF
C1= 1 uF
C12= C1 + C2 = 3 uF

V - V3 - V21 -V2 = 0
V = V3 + V21 + V2 = Q/C3 + Q/C21 + Q/C2 <--------Solve for Q
Q=V/[1/C3 + 1/C21 + 1/C2]

V21 =Q/C21=V1
U1=(1/2)C1*V1^2