Can Communication troubleshooting

[otrotabi]

We have two chillers which are connected using CAN binding with TM172PDG18R controllers.  I set up communication following the attached tutorial.

Both chillers have exactly the same program, so the binding table is exactly alike as defined at HVAC installer.  I added some variables to both tables and at some point, I could no longer see one of the variables from PLC Node #1. Only one of them from a list of nine variables.

To make a long story short, I decided to start from scratch and followed the same procedure again from zero except that my binding table consists of only three variable now.

I can see some variables from from  PLC #2 on PLC #1 but not from the PLC #1 on PLC #2.

So far I have : 

1) Made sure both PLCs have the same program.

2) Made sure I downloaded the binding table to each PLC

3) Checked physical wiring. From both sides I can read 120 Ohm between + and - 

I am running out of ideas actually. What else can I try ?

EDIT .....

Tried for the nth. time and it seems to be working now again. However, I did not learn what might have gone wrong. Is it likely to start failing like this or definitively I f..d up somewhere ?