Dark stripe and light roots

Hi,

I have a problem with my blue/green hair. When I started dying my hair I used directions alpine green. Because I wanted to achieve a more blue colour I added some midnight blue and applied it after I bleached my roots a few months later. The blue attached more to the bleached part so the top of my head was bluer than the lower part, it looked good though. After bleaching my regrowth another time a few months later I decided to add arctic fox transylvania to darken my hair a bit, and I mixed it with midnight blue and alpine green from directions. Since this dying session my hair has a dark blue line, marking the line of the regrowth from before. My newly bleached roots seem to fade very quickly. I tried several times to apply a lot of transylvania and midnight blue to this specific area, but the line is quickly visible again after a few washes.

Long story short, I have this weird blue line in my hair and my roots won't absorb arctic fox, so it seems.  Any help?