RadGridView with Observable Collection

[Rocio]

Hello!, I have a RadGridView, that it's itemsSource is an Observable Collection, and when an item of the collection changes, it also changes in the RadGridView, the problem is that the changed element moves to the last row, and I don't want it to move, or to move to the first row, but not the last, anybody knows how to change it? or how I can get the RadGridView ordered when it happens?
Thanks!