Hi Mike,
There are a number of possibilities.
1. Not all Nuvis send the GPS signal through the USB port to the PC. On many Nuvi models the USB connection is only used to transfer waypoints, tracks, routes and maps between the Nuvi and Mapsource.
Are you sure your model sends the GPS signal out the USB port to the PC?
2. Whether your Nuvi sends the GPS signal or not, Streets won't do anything with it anyway. Streets has no clue how to connect to the USB port. The only thing it can connect to is a COM port and only at 4800bps. There is no other way to connect a GPS receiver to it.
The only way you can connect your Nuvi is using
GPSGate. It will detect the GPS receiver on the USB port and it will create virtual COM ports to output the signal at any speed you set it to. That way you can make Streets happy by setting one of the virtual COM ports in GPSGate to 4800bps and pointing Streets at it in the Configure GPS page.
GPSGate is not free but there is a free 14-day trial so you can find out if it will work for you before you have to decide whether to buy it. And it's only about 13 bucks (
GPSGate Express) if you decide to buy it.
EDIT: Okay, it occurs to me someone's going to suggest Xport or Spanner so I might as well deal with it myself.
Xport won't work for this. It won't accept input from either USB or Bluetooth directly, only COM ports.
Spanner might work but it's old and I don't think there are many Nuvi models it will work with, if any. The odds are slim.
GPSGate is guaranteed to work for this purpose if the Nuvi model Mike has outputs the GPS signal.
PS. Oops, I didn't see Terry's answer before I entered this. I hope I added enough value to leave this here.
...ken...