Do not select more than 28 objects that require terminals to create a subVI from a selection because 28 is the maximum number of connections on a connector pane. Each block diagram terminal, each front panel object with a Property Node, and certain local variables you select require a terminal on the connector pane. If you select more than 28 objects that require terminals, LabVIEW displays a dialog box describing why it cannot create a subVI.
To avoid exceeding the maximum number of terminals, select a smaller section of the block diagram or group some of the objects into a cluster.