Partial communication between Panelmate 3000 HMI and PLC

[blackmrl]

I have a peculiar issue we're trying to work through where only some commands from our Panelmate HMI are making it to the Schneider TSX PLC. Simply put, we use the HMI to Open/Close valves, when the operator selects a valve he then hits an Open or Shut button and it sets a variable to the PLC to 1. For some valves, works no problem can open/close but for other valves no control. Now, that same PLC that fails to Open/Close the valve does pass the valve status and other control functions to and from the PLC so we've established communications between the specific PLC and the HMI however we do not have valve control in some cases. This HMI software works on identical previous systems and we've double checked the PLC Bit References which are correct. The question is why would you get some control communication from the HMI to the PLC but not all controls? It would seem if there was a comms problem you wouldn't get any communication between the two. Communications is a little complex, we use a bridge to connect the HMI from RS232 Modbus Serial connection to Ethernet and then Ethernet to a switch. All PLCs and HMI are interconnected via a fiber optic network through switches at each PLC. Comms status appears fine. At the HMI panel, we have the executive firmware set to 5.60... and use a Modbus RTU driver. Anyone familiar with the Panelmate HMI have any ideas?