How to select with ruler mm

#target photoshop

app.preferences.rulerUnits = Units.MM;

var w =  activeDocument.width.value;

var h =  activeDocument.height.value;

selReg = [[0,0 ],[0 ,h ],[w ,h ],[w,0 ]];

activeDocument.selection.select(selReg);

I would like to make a selection with ruler mm.

But I can't.