Dividing root-balls
 

My favored plant for bonsai is english ivy. I know it's not the usual
kind of plant, but I like a challenge. I recently got (another) ivy
plant from the local nursery and decided to try to divide the root ball
so i'd have one good branch to start with rather than the cluster i've
been working with. Now the single branch/stem's flowers are looking
droopy and not turning to face the sun the way the other ivy plants do.
What'd I do wrong?