Hair will not take dye

My hair has stopped taking dye now for several years. Every time I have tried to dye my hair there is no difference. Realize that I had been natural for the past 7 years so there were no chemicals in my hair whatsoever. I am not on any medications which I saw some where that that can cause for your hair not to dye. I have been getting blowouts but not frequent, maybe twice a year if that much. But the problem started way before I had my first blowout. I finally got tired of the natural look and got a relaxer this past December. Been wanting to add highlights to my hair but opt to go to a stylist since I have been having bad luck coloring my own hair. I thought maybe I am just not doing it right or maybe a box color is just not for me. So I also opt to get most of my hair chopped off. Just got tired of long hair and wanted something that did not require to much maintenance, so my hair is very very short right now. I explained to her the problems that I was having with dying my hair and she seem confident that she could make my hair take. She put the highlights in and sat me under the dryer and checked on them a couple of minutes later and said that it was taking just fine. By the way, I was getting copper highlights. After got me from under the dryer she washed my hair and put a deep conditioner in it and sat me under the dryer again, then washed it out and smoothed my hair down and then back to the dryer to dry my hair. When she went to style my hair all the copper was gone and I was left with blond highlights. This same thing had happened to me before. I told her not to worry about it as I had been debating between copper and blond for a month and I guess someone up above decided to make that decision for me. But she was determined to do some research on what could have happened.

By the way, I don't know if this has anything to do with anything but may hair naturally lightens on its own. I would say from about two to three inches from the roots it gets very light. I have dark brown hair at the roots any hair will lighten to a honey blond. I can tell you that I do not spend much time in the sun as me and heat do not get along. When I would go to a stylist, every single one would tell me that the highlights are damaging my hair. When I would tell them that they are not highlights and that it is my natural color they would look at my like I was lying. 

Your hair is too porous to hold color. Until you grow new healthy hair, you can't do anything to color it.

Right now your new (lighter) growth is not healthy.

Hair color depends on the pigment melanin, which is produces from amino acid tyrosine. If your hair grows lighter, you have problems with pigmentation producing. Because amino acids are proteins, you should consume more of it. Have you been dieting lately? It may be the cause. You should eat chicken, meat, fish and eggs daily. And because it is not just beauty issue, but health issue. Do not look for advises on forums, visit a doctor, you should seek for medical help. Check for hormonal imbalance and mineral and vitamin deficiency.