The same thing also happened to me!
I use the same brand; it's actually excellent. The reason your color didn't take is because the developer in the kit isn't strong enough...which is a good thing.
I started off with T&T Light Golden Blonde. It just lifted my color just a little, maybe 2 shades.
A month later, I used Bronze. It looked nice, but it definitely did not match the shade on the box!
Then, the next month, I used Honey Blonde. It worked! That kit also includes a powder booster that really strips the strand and deposited the color a bit TOO well! LOL!
Once it oxidized and settled a couple weeks later, it was gorgeous!
I studied Tracey's Bootcamp (it's a sticky thread) and followed it, since I'm relaxed, and I have had no problem with breakage whatsover and I have lots of moisture.
What works:
1) Be sure to DC at least twice weekly to prep your hair for the lighter shade. Be sure to DC at least once weekly post-application.
2) Right before coloring your hair, clarify. This will strip all the coatings and buildup that prevent the color from getting in properly. Do NOT use a conditioner, leave-in or regular. Be sure to blowdry your hair after detangling.
3) Use a timer and process according to the manufacturer's instructions.
4) After shampooing, be sure to DC for at least 20 minutes WITHOUT heat.
5) After rinsing, apply Porosity Control and process about 5 minutes.
6) Rinse and style as usual.
I also color another LHCF member's natural BSL hair in various hues of bronze, blonde, and ash. She gets lots of complements, whether she wears it curly or straightened.
The stylist who cuts our hair actually offered me a job at his salon because he's so impressed with my results.
Hope that helps. I'm not subscribing to this thread; so, if you have any questions, don't hesitate to PM me.