Grid with smDisjunctRow

I have a grid where the selectionmode is set to smDisjunctRow.
I do a clearrowseelct, and fill the grid with data after that (via the onGetCellData event). So far so good. But it will always select the very first row. Why is that so? When clearrowselect clears the selection, it should stay cleared and not reselect the first row after I load data into the grid.

Can you share the code that you use to clear & reload the grid?