Encountering Auto-Number Problems When Repainting

I am trying to repaint the numbers on the DTG C40-8 from white to yellow for the cab section. I have successfully changed the font of the numbers and I have added the new color, but for some reason when I load up the locomotive, the numbers appear darker than they should. I have noticed when I went in to import and save the alpha layer for the numbers, they get darker after saving and closing. The alpha layer does not want to seem to save properly. I have attached a few screenshots to show what I am talking about:
If someone could possibly help me get these numbers to show up on the locomotive correctly (meaning bright and not dull) I would really appreciate it. Finishing up those numbers will be the only thing that I need to do to complete a repaint that I'm sure everyone will enjoy.
Thank you very much
If someone could possibly help me get these numbers to show up on the locomotive correctly (meaning bright and not dull) I would really appreciate it. Finishing up those numbers will be the only thing that I need to do to complete a repaint that I'm sure everyone will enjoy.

Thank you very much