When asking for technical help at the very least let us know the version of firmware you are running.Cliff's Calibration (Mapping) Guide is a MUST READ: http://www.vemssupport.com/forum/index.php/topic,97.0.html
that's not the way you do it I mean, why there is a pushbutton?
I'm not so sure that both of these functions can use the same input. Enable and adjust at the same time. Maybe it will work? Personally, I'd try it with the first diagram, as the voltage divider will just make the control less granular. That may be an advantage at the end, but try without the voltage divider first.