This may not be relevant to you, but....
I had trouble connecting my nav5 to my PC using Mapsource. So try this-
To make it connect you need to fiddle with the settings in your Nav 5 and change them to Mass storage mode.
Here's a copy of my post
I have a Nav 5. I use Mapsource as I prefer it. You keep Basecamp, I don't want it, or like it, or want to use it. It doesn't do,what I want...
To change your Nav 5 settings to Mass storage mode you have to access a hidden menu. My Nav 5 has just gone back to Garmin to be replaced so I have to do this from memory
Find the page with all the past info on it, max speed, average everything, time travelling, time stopped etc. I get to it by touching the 3 horizontal lines on one of the tabs on my dashboard.
YOy should get to a black and white page with loads of info on it.
NOW... press and hold the speed ummm button at the top(?) until you get the hidden menu come up.
Scroll down to the last page, and press the MTP radio button to switch it on. It doesn't upset anything else I'm told.
Now your Nav 5 should be recognised by Map Source.
Any luck?