There are several reasons that a problem might occur when selecting a steel connection in a structure:
- incorrect number of selected bars 
 
- incorrect section types that do not correspond to possible connections 
 
- bars are separate, or bars do not lie in the same plane (take note of the coordinate precision) 
 
- rotations of bar sections with respect to each other, which do not fulfill the connection criteria 
 
- lack of the active bar section database (in particular the Catpro section database) 
 
- inappropriate geometry of a selected member group for a given connection.