They should all be 100 percent valid codes.  I will send you a PM and get it fixed up.  Been selling since  July 30th 2015 of codes and have made every customer happy.  That is a record none of my computation can touch.  You will notice some of computation say's "NO Refunds - All Codes Are Working." this is due sadly to amount of people who try to say a code is invalid and get a second code.  I so far have eaten cost to make sure I can give best customer service possible.

Just in general when buying please make sure you have not used a "MLH 2015 Hackathon Season" code. It does not stack if you have used this event before on your account.  So even if 6 months ago you used it... no stack.  Many use new accounts if they deal with codes in past due to the events not stacking.