cannot connect to messenger server

I’ve just installed the free comodo firewall (version 4.0.141842.828) and now, when my son plays “Combat arms” he gets an error message within combat arms, “cannot connect to messenger server”. I think the firewall is blocking the connection.
I tried to add the combatArms.exe to the trusted vendors list in Defense+ but I get “The file does not seem to be a valid signed executable”
I then tried to add the combatArms.exe in the “Define a new Trusted Application” in the Firewall tab but im not sure it worked because I cannot see where to view my trusted application, also the problem still remains.
Any suggestions welcome.
DS

I then tried to add the combatArms.exe in the "Define a new Trusted Application" in the Firewall tab but im not sure it worked because I cannot see where to view my trusted application, also the problem still remains.

You have defined a new rule with combatArms.exe.

Go to the Firewall> Advanced> Network Securiy Pollicy. It should be there.

Check if your son would not have blocked a firewall alert, in the same window. Also look for the same reason in Defense +> Advanced> Computer Security Pollicy.

You can find combatarms.exe being a trusted file in Network Security Policy → Application Rules → you will see it there with a rule that allows all traffic.

You can try adding to My Own Safe Files in Defense + (when it is in My Pending files move it from there to My Own Safe Files).

With combatarms.exe in My Own Safe Files does the error message return or not?

Thanks for the repliies.
I’ve done a bit more digging and combat arms has at least 3 executables that it runs: combatArms.exe, Engine.exe & CAV.exe.
As EricJH says: CAV.exe is in :
Firewall> Advanced> Network Securiy Pollicy
but not the other 2.

I took Drakeine’s advice and added Engine.exe into My own safe files.
I did this by selecting Add/Browse running process
however the other 2 exe’s are not there, i think maybe they are only used when the game starts up
I’ve tried to catch them with Browse running process when combat arms is booting up but without success.
So I tried to add the whole combat arms directory in “My own safe files” using:
add/Browse files
I can select the directory, copy across to the right hand side with “->” then, apply the settings but nothing happens and the dir doesnt appear in the allowed list.
Any idea what im doing wrong here (i don’t get an error message)?
So bottom line is the error remains.
DS

Set the firewall to training mode,defence+ to clean pc mode, disable sandbox. Then launch the game and wait a minute then exit the game. You should then check the network security application rules to see if anything new was added, then check my pending file under defence+ and move to my own safe files.