Help listening to Seattle FD Trunked.ws1080

I programed my scanner with EZscan software using the import from Radioreference. I imported the Seattle Fire and PD without problems. However I have scanned for over 24 hours on different days, and have only rarely heard a transmision. I have been indoors/outdoors and all around the city and hear no activity even though calls are going out. Conventional systems work fine. Do I need to use a different than stock antenna to better hear trunked systems? If not what am I doing wrong.

Help listening to Seattle FD Trunked.ws1080