ListView ScrollIntoView problem

Question

I'm trying to scroll into view the last added item to a listview control that I called trackBar

the problem I use this same code in my win 8.1 app and it works fine but the same app targeted win 8 made in vs2012 won't have the same effect

this is what i use:

TextBlock tb = new TextBlock
tb.Text = change;
trackBar.Items.Add(tb);
trackBar.ScrollIntoView(trackBar.Items.Last());

why this works for with vs2013 and win8.1 and not vs2012 and win 8?!