If this is the case, please check in the layers if a layer "AM_0" was created. This only happens after you send the crane from CRANEbee to AutoCAD. What it means is, that the target drawing was created in AutoCAD Mechanical and not "normal" AutoCAD. As those are two different programs with completely different object behaviors, CRANEbee can not correctly connect to drawings made and saved in AutoCAD Mechanical. Even if the file format is .dwg.