Hi, am new to cake central so here goes... the food colouring that you use is important, I use Silver Spoon red Food Colour, and it is a real popping red, and all my red velvet cakes come out red, give it a try, I also used the recipe from a site called...joyofbaking she is amazing, have a look...Hope this has helped.
I use Sugarflair Red Extra for my RV cakes/cupcakes. I use 1/2 tsp for 12 cupcakes aprox. It will depend on your recipe though. The colour usually darkens in the oven but the batter has to be bright red in your mixer bowl before baking. Mine come out looking more burgundy rather than bright red when baked, but that's the way I like them (and it's my bestseller so others must like them too!)