Generally everything you want to communicate with a switch should be connected and communicating (including nodes on other daisy chained switches) before you lock the switch. When you lock a switch, idle ports are locked and prevent communications through those ports.
Before you lock a switch, look at the Node Name column in the Port Details pane in the Network Device Command Center (NDCC) application. The ports marked with (Idle) are not communicating with other devices. If you believe a port showing (Idle) is connected to another device, verify the connection and communication before locking the switch. If the port is idle when the switch is locked the device will not be able to communicate with the switch.