A question for hairdressers...hair dye problem?!?

recently, I bought the dye i normally use but from an unfamiliar website due finding the product at a marginally lower cost than normal. It is a 'Wella Koleston Vibrant Reds 55/65 Light Intense Violet Mahogany Brown' as it was from an unfamiliar supplier i decided to do a skin test just to make sure it was ok to use. Fortunately, i found my skin to have no adverse reactions to it However, The first time i used this dye I performed a skin test it went a pinky/red wine colour which is the colour it is supposed to go on the hair. With this skin test the patch has gone bright yellow...what does this mean? is it safe to put on my hair? x