Move the antenna several feet and try again. Rinse and repeat as needed.
TV signals are often cantankerous and they don't necessarily make themselves appear where we decided an antenna would be convenient. Trees and other obstacles will more likely make the situation more pronounced.
The five character call signs are translators (relays). You can usually look them up at
www.rabbitears.info Wilmington is market # 152 on that listing. You can also usually Google the call sign. Be aware that just because there's a license that TVFool has pulled from the FCC's database doesn't mean the station is actually on the air.