Did you use the Powder in the Boil or "Dry Hop"?
I tried the Powder one time in the Boil and the other as a dry hop to attempt to reproduce a Youngs Double Chocolate Stout. I received very different character results from the chocolate in both cases.
I put the chocolate in the boil last 5 minutes, and dry hop was placed in when yeast dropped out, and essentially left for two to three weeks until the flavor development was at the level I wanted.
At some point, I am going to try a chocolate extract and see if that is just easier. If I do not like those results, my plan is to play with ratios of chocolate powder in the boil and dry hop to see if I can dial it in better.
In my opinion, the chocolate in the dry hop never really settled out, and gave me a bit of a chalky sensation when drinking the beer. I was thinking of using a fining if I dry hopped chocolate poweder again.
Also, the chocolate in the boil gave me much more of what I was after, but either I did not add enough or the flavor characteristics were not quite what I was expecting. When I blended the two beers, however, I was very close to what I wanted.
Hope that helps, and Good luck.