Hello there. I am having trouble in the purlin and cross sections of the project I have uploaded in the attachment. When I change the cross sections of purlins or diagonals, I get the error "The system cannot be resolved". When I checked it from the 3D view, I saw that the purlin-truss connections or cross-spring connections disappeared. In short, they are in the air. When you change the direction selection in the diagonals and restore it, the links come back, but after the analysis, they disappear again. I would be glad if you could help with the matter. Thanks.