Red Velvet Success and Another Frosted Mess

In connection with the S'Mores mix purchase at World Market, I also bought a red velvet with vanilla bean frosting cake mix from sof'ella. So, I baked red velvet cupcakes last weekend at varying degrees of success.

The cake was fairly simple to concoct and turned out very well. It raised better than other store bought cake mixes I've used in the past and the consistency was somewhat dense, but with the right amount of moisture. As for the frosting, well, it turned out too thin again. The mix didn't call for powdered sugar, but I added it in an attempt to thicken it. No luck. The frosting tasted good; but dripped everywhere. For the sake of the pic, I cheated and ended up using tub frosting.

I'm not sure what's going wrong with the frosting. I'm following the directions. Even this time, I used the minimum of the two to four tablespoons of water that the directions called for. If anyone has suggestions on my frosting dilemma, please post them in the comments.