Remembering scroll position in PropertyGrid

I have a CXTPPropertyGrid which I empty and repopulate each time a user clicks between items on a CXTPReportControl. When the repopulation is complete, the scrollbar and scroll position of the PropertyGrid always reset back to the top, which can be frustrating for users if they are viewing fields at the bottom of the scroll view, so I'd like to be able to store the current scroll state of the property grid prior to updating, and reapply it after the control has been repopulated. The property grid will always contain the same number and type of fields so it is safe to re-use the scroll position, but I'm just not sure how to do it.

What I have tried so far is:

SCROLLINFO si;

CXTPPropertyGridView & vView = pPropertyGrid->GetGridView();

vView.GetScrollInfo(SB_LINEDOWN, &si);     

int nOldPos = si.nPos;
//Do repopulation stuff
if (si.nPos != nOldPos)
{                    
     vView.ScrollWindow ((nOldPos - si.nPos),0);
}

But this doesn't seem to work. I've also tried 

vView.SetScrollInfo(SB_LINEDOWN, &scrollinfo);         
and
vView.SetScrollPos(SB_LINEDOWN,scrollinfo.nPos);
but they didn't work either, so I'm stuck as to what to try next. 
Any help would me much appreciated
Eric

Thanks for your reply. I tried GetTopIndex but it returns 0 every time regardless of the scroll position of the the grid. I also tried invoking GetTopIndex on the property grid's view member object but again , no difference.

Eric