painting with dark colors
You should be using a 3/8" nap Purdy White Dove roller - you need to wet it and make sure it is damp before you use it - this helps the fabric load and release the product evenly.
Apply the product at about 300 square ft/gallon - this is about an 8x10 room - one coat. More than that and you are spreading it too thin - which hurts hiding.
Finally - dark colors don't hide as well as white - sometimes you need a deeptone primer. Behr doesn't make one (and Zinnser Deeptone is a waste of money - it doesn't tint dark enough) Look for a RL color next time -- RL has a deep tint primer - which works very well.
If you are not seeing the other color then you are rolling uneven and or too much in a certain area.
Alot of times I see home owners rolling out then using the roller in a little spot that was to thin only making that area darker.
As for Behr's recommendation of tinting a primer close to a color - try this:
Pick one of their red colors - the deepest one you can find.
Tint their primer with 5 oz of red colorant.
The primer will be the color of Pepto-Bismol.
Try and get the red topcoat to hide over that pink in two coats - it won't happen.
Now try a RL red - maybe Hunting Coat - use the RL Deeptone Primer.
Your RL topcoat will cover in two coats - guaranteed by ICI.
I do this all the time - this is how it works.......try it if you don't believe me.
Hope this helps out.