Its correct, you need to use NPT threads, not a flared fitting on that side. I ran into the same thing, I ruturned it and had summit send another only to find the exact same thing. I put a pipe thread fitting on that side, and it works fine.

To the last question: Pump the brakes to full pressure, then hit the switch to lock the line. Although, you can hit the button and then push the brakes, as it is a 1-way valve (WON'T let pressure out, but WILL let more in).