Pensengr, make sure the SAP snap tools are activated correctly, particularly the "snap to midpoint" option, and "snap to grids and joints" if there is a grid intersection or joint at the midpoint. Without the snaps being activated, it's easy to miss the precise point you are trying to connect to when drawing frames or joints. By the way, I note that you use the term 'join segments'. Are you talking about connecting adjacent frame elements which are disconnected, or are you talking about drawing a new frame connected to the midpoint? Give more details about what you are tyring to do if the snap tool suggestion does not work.