I had to call in and have a rep ticket for me ... it was no problem (and had nothing to do with the Florida restriction...in fact, after I gave the rep my codes, she only saw the restrictions related to purchase-by date and fly-by date).
The issue is the base fare being below the discount amount....which necessitated the call. In one call, the rep was able to book a roundtrip for me and apply 2 discount codes for $50 off.