but what length is the bulb or bulbs? that will help us determine the wattage.
Something important to consider, a 55g tank with standard lighting really isnt that bright. Not that it wont do, mind you. The plants arent going to go as crazy under that light (im assuming its a standard single width fixture) but they can still grow, and grow healthily. Some plants might need more light than others and ultimately might need to be replaced with a species that tolerates lower light levels. Conversely, some plant species thrive under low lights (i.e. anubias sp.).
What I believe is most important, is having some patience at this stage. The 'mother leaf' that Ive always received my water sprite on has always browned initially, but the new growth on the leaves themselves have been unreal. The anacharis and vals might just need some time. Every time I move a plant from tank to tank or even just to a different spot in the same tank, growth stops until it gets readjusted. It could take hours, or it could take weeks.
The vals could simply just be adjusting to your water. Most plants will grow differently and at different rates based on temperature, water hardness, available nutrients, etc.
Give it some time, and in the mean time measure that bulb for us!