It's crazy that they don't tell you what was wrong. I know lots of people defend them for rejecting applications on technicalities, not telling why they are rejected, and keeping the money. I think those people are crazy too.
I'm referring to the fact that people applying for tourist visas or pretty much any kind of visa to the USA are often rejected with no explanation after having paid the fees.
FYI. If circumstances ever require you to go there again you can make an appointment online and that works great. In and out in half an hour. Appointments, however, are limited. Just Google 90 day online appointment.