我最近也遇到了这个问题，全网搜索也没有找到满意的答案，为此我查看了软件自带的文档《padslogic_user.pdf》,希望能够帮助大家：
在这一节中：
Adding Connections
When you add connections, they must have start and end points that are electrically meaningful.
Start a connection on either a symbol pin or another connection. End a connection on a symbol
pin, another connection, a bus, an off-page reference, or a ground or power symbol. PADS
Logic prevents you from starting or ending a connection just anywhere in the database unless
you enable Floating Connections.
明确地说了任何一个connection 必须连接到有意义的节点上面，或者管脚，或者off-page connector或者电源，或者另一个connection.  PADS logic阻止你随便开始或者结束一个connection, 也就是说 connection 不允许悬空。 但是文档又说了。除非你使能了 floating connections.