Mark,
You should see a significant jump in signal strength if everything is working correctly. On FM you will hear little or no change in background noise, but in SSB that should be very apparent.
Two things to check. The first is to make certain you have the antenna and feed line going to the right connections. It sounds obvious, but many have gotten them backwards. Best not to transmit through it that way. ;)
The other is whether the DC voltage is getting to the unit. Power using the coax, or separate DC power cable?
If the first, make certain you are getting 12 volts from your rig. Check for 12 volts DC on the rig (or bias T) antenna jack, and that you have a DC connection to the unit. Most TX amps have capacitive coupling which will block the DC. Verify 12 volts at the antenna feed at the unit.
If the second, check 12 volts to the connector at the unit, and that it is going to the right pins. It is possible to make up a little test jig with a multimeter and check the current draw.
Good luck, and let us know what you find.
Alan WA4SCA