Connectors not connecting anymore

[Cornea]

Hi
I have a process flow and all my connectors are connected to shapes (red dots on handles).  If I break a connection, I cannot get the connector to link/connect to the handle of the shape!  I tried new connectors, they also don't want to connect.  If I create a new drawing, the connectors link to the shapes.
Can anyone explain this to me?
Thanx
Corne