Beam Joints

Hello,

I have some problems to resolve the beam joints in my Karamba model. 

I'd like to build a truss but when I allow the rotation the AnalyzeI module send an error message : 

The model works if all the translations and rotations are blocked. 

Are they some other way to get a truss and modelize rotules? I read somthing in about puting bending to zero but I can't find it in Karamba. 

1. Singular Stiffness-matrix: Can not solve static system.
Make sure that boundary conditions are set so that the structure can not move in rigid body modes.
When you analyze a flat shell structure lock the rotation perpendicular to the plate in at least one node.
Use the 'Eigen Modes'-component and activate the display of local coordinate axes: The first eigenmode will be the rigid body motion.

I attached my file If needed,

Thanks,