I keep dying my hair and it wont get darker??? how does this make sense?

my hair has been bleached for a while, and i want to dye most of it a dark blonde and leave the bleached streak in the front. yesterday i used a semi-permanent dye to dye it all a dark honey blonde and left the bleached streak. i let it set for 25 minutes, washed and shampooed it out and my hair was BARELY a little more yellow than the platinum i left in front. today i went to get a little darker tone thinking it would work, a light brown and repeated everything.... and its still BARELY any darker. do i need to wait more time??? or use a darker color? i have no idea how this is even happening.