By default, when the user scrolls to the last pip the navigation button looks disabled and it can not be clicked. This behavior can be changed through the IsInfiniteScrollingEnabled property. When the IsInfiniteScrollingEnabled property is enabled it allows infinite scrolling from the last pip to the first pip automatically and the same in vice versa.
Enable Infinite Scrolling
this.radPipsPager1.IsInfiniteScrollingEnabled = true;
Me.radPipsPager1.IsInfiniteScrollingEnabled = True