I don't know how the sweeper works, but with close call on my sds100, I think it measures the rssi level. So it has to be over a certain number for the scanner to both looking for it.
If you have a target or walmart, mall near you, sit in the parking lot and see if that works. If it doesn't, then something is wrong. I know my trx1 scans super close compared to my sds100 but I still get 90% of the same hits on the trx as the sds. I don't use OEM antennas though. The stock one on my trx is horrible.