Scratch2 does not work - script box does not move

Hello, We just started using Scratch2 on Kano (OS v4.3.3). When we try to drag one of script boxes to the right coding area, it does not move at all. So we cannot do anything with it. When we click the script box, the cat does an action based on the script, so it is not like the Scratch/Kano is frozen. Has anybody experienced this?