Dyeing Clothing?

I dyed a white nylon dress yellow, wore it twice, and then noticed it had tiny orange spots where apparently the dye didn't blend completely. I washed it and hung it to dry. Then I used a toothbrush to lightly scrub in a 1:3 mixture of Dawn and peroxide on each spot. I washed the dress again, and hung it to dry. The spots remain. Do you have any suggestions?