This could be caused by several things.
Make sure the controller is set up for BACnet/IP. An MLX/MLS controller will not be able to see any of the control stations if it is set to MSTP. Go to "start", "setting up"", "other", "network type" and make sure the type is not MSTP.
The station must be set up in the controller. Check "start", "setting up", "hardware", "stations" and make sure that the station is set up correctly.
If the control stations are all blinking in unison, it could be the A4 network has a blown communications chip. If you suspect this may be the case, there are 2 comm chips, one can be swapped to the other position if the cabinet is not networked to other cabinets. Call Synergy Technical Support for assistance in swapping the chips. 1-800-535-2465.