Select a top face and not an edge. If you select an edge, right-click the selected edge of Boss-Extrude 1 part and click Select Other to select the top face from the list. You can also press F5 and click Filter Faces (Selection Filter toolbar) to restrict selection to faces only.
Select a top face and not an edge. If you select an edge, right-click the selected edge of Boss-Extrude 1 part and click Select Other to select the top face from the list. You can also press F5 and click Filter Faces (Selection Filter toolbar) to restrict selection to faces only.