In LonMaker or OpenLNS CT you can create master shapes and store them in custom stencils to re-use as many times as you wish in designs. A master shape can be any object with custom properties or a collectikno of objects such as functional blocks with specfic connections.
This error will be created when you tried to place one of those master shapes on the drawing. The shapes will most likely have contained one or more network variables but they do not exist in the network. LonMaker tries to match what you place in the drawing to the available resources in the nbetwork. In this case the network variable contained in the master shape must exist in one of the deivces already in the database. If the variable in question was a dynamic network this would need to be created