Hello, I have an assembly with rotational joints model using a pipe and an O-shape open cylinder. The joints rotated but after I imported the assembly into another one, they don't turn anymore. I know that I should go to the properties and change the setting to flexible using the procedure described in:

2012 SOLIDWORKS Help - Flexible Sub-Assemblies

However, that option is dimmed. It can not be chosen. Any advice on what to do? Thanks.