Scissors are not working in slicer in kindly help

Operating system:windows
Slicer version:4.10.2 and 4.11 preview

sequence of steps
loaded sample CTChest
opened module segment editor
created two segments
created a mask by using threshold to seperate out the airways and lungs
generated a 3d model using grow from seeds
used segment statstics to generate volume of lung with airway
tried to use scissors to cut out the lung lobes so that only the airway remains behind , but the scissors wouldnt work
plz help

A post was merged into an existing topic: Scissors are not working in slicer in 4.10.2 kindly help