I'm not sure if I understand you correctly, but when using the probe the machine asks you to jog to a start position which you seem to be doing. Then it asks you to jog to the opposite corner of the area you want to scan. You must use the arrow keys to do this, if you try and hit enter before you do this nothing happens because you are telling it to start and end at the same point. I hope this helps you.
You might want to view Carve Buddy's Scanning Probe video, it will probably answer your questions. Here is the link
http://www.carvebuddy.com/scanningvi..._it_works.html
When everything is coming your way, you're in the wrong lane.