Thank you every much.To see the unit cell both ,one need to drag both icon to the view in the left panel ,not in the right view botton.If you use the right view botton ,no matter how you try to pick the two icon and insert the botton ,it can't work. It's a slight bug but not affecting the usage ,Hope ATK can fix the problem in the right view botton .Two pictures using left view icon and right view botton are in the attachments.