Attaching/assigning materials in AECOsim Connect?

Hello,

I'm testing the new release of AECOsim Connect 10.00.00.118.

Why is it not possible to attach or assign materials to volumetric elements like Linear Forms, slabs forms...?

See attached screenshot.

When assigning the linear form by selecting it I get the massage "Element not valid for tool"??

 

Sincerely,

Wim