Problem with WMI displaymanager setgridpositions

I create successfully two grids with one monitor in each with displaymanager.createdisplaygrids(“rows=1;cols=1;mode=1600 1200 32 60”,“rows=1;cols=1;mode=1600 1200 32 60”).

The monitors are physically placed on top of each other, so I would like to move the two grids.
I have tried with displaymanager.setgridpositions(((0,0),(0,1200))), but I only get failure as response, nothing happens. I have tried with different values, but setgridpositions allways returns failure.

What am I doing wrong?

Regards Audun