But when I got home and try to use it from www.wadiscount.com they obligate to pay the shipping which is not covered by the gift certificate, and the shipping fee exceeds the actual selling value of the items. I did some research and found out this is a scam site.According to
Gift Certificates of America, Inc. has a BBB rating of F.
And once I input my credit card info, they may be used for Identity theft also.

I contacted EXPO PRO and asked about thesituation, but they say they arenot aware of any problems with the certificate, but that's not true. They been using this prize for several events already and here I found other people complaining for same issue:

They are gathering people with false prize which is worthless, and tricking Expo visitors including little babies, I can't supress how my little baby got fooled by this guys. We need stop this Expo.