I have a problem. I have AutoCompleteTextBox and TreeView, both work with the same SelectedItem.
The node must expand, when the user uses AutoCompleteTextBox, but it only works only if I expand node per MouseClick and Collapse it.
I am not quite sure how you implement this requirement but you have to know that the RadTreeViewItems are generated when their parent is expanded or when they are root level items. In other words, you may have come up with a situation in which you try to expand an item that is not prepared yet.
However, I strongly suggest you to look at our OrgChart demo demonstrating similar functionality. Expand the Blue Button on the Right. When you choose a person from the RadComboBox, it's corresponding item from the RadTreeView is being brought into view. The method used in the RadTreeView is BringPathIntoView() which is ready to bring a not-prepared RadTreeViewItems. It actually forces the generation of items in the ItemContainerGenerator of the RadTreeView. Please find its documentation article here.