Youth Hair Creme 16 oz. (Case of 6)

I'm been using the product for 21/2 weeks and not results yet. I was amazed to see how this product worked so good in the friend who recommended the product. I had followed the instructions very close, even exposing my hair to the sun for several minutes, but my gray hair still there. The only changes I had noticed was a light color in my gray instead of a dark color that I will like to have. I do color my hair before, and one of the tips is not to mix it with any hair dressing.