Help with red sea mg test

Does any one have a red sea magnesium test kit. I have tried to use my test kit 4 times now and it has not worked once it goes from the red start color staight to violet wich is ok but it never reaches the blue end point if anyone has info on one of these kits i would greatly appreciate it thanks

 

Once it turns to purple, that's where the Mag level is. It never really gets that dark blue color like on the card. That's it. Don't waste any more of the "C" bottle than you need to.

 

yeh there kits vary so much, the old one i have I was able to archive the blue color but the new one i bought doesn't.
Like Bogie said when it turns purple take that for your mag reading.

 

thanks guys that answers my question