Problem after replacing dash brake valve on 04 VN 670

I have 04 670 with ISX. I had some air leeks on quick connect fitting on dash brake valve. Called a few dealers and they all want $400-440 for updated parts 85123221 which is one made by bendix and have 5 port. Mine original have 6 ports and tiss 6th port goes to the TRL hand brake. So new 5th port one have 2ft air line and T and 90 fitting so you can splice that trl hand brake valve into 5th green port wich is supply.
I found new original Meritor Wabco brake valve volvo # 20523171 or Meritor # RKN20619 from Advantage truck centers in Charlotte NC for $230
So after i installed i found out if i drop air bags on drives or if i use air blower/seat air it will use air from F air tanks. But for everything else such as red air suppy for trl or yellow parking brake or foot brake it will use air from both F and R tanks equal. So now driving down road on flat after about 16-20 minutes only F air tank loses air and compressor charger back at 90 psi to 120 ps. But R air tank stays a t 120 psi whole time. R air tank only looser air if i apply foot brake. Before no matter what i do like dump drive air bags, use air blower or driving down road both F and R air tanks (needles) will loose air together. I know R air tank gauge works so thats not issues. Also i conncet all air lines on right port and all ports on old dash brake valve have same markings like new one. Old one was built back in 2003 new one in 2014 and they looks same to me
Maybe this new dash brake valves have different setup so drives air bags uses air from F air tanks ?
Thanks

 

Yeah but what brake valve have to do with accessory air like seat. Should airbags on drive be on R tank but before in order to air them up they were using air from both tanks now just from F tank. Does all air goes thru this dash brake valve ?

 

Update. I bought another dash brake valve. This time new volvo updated bendix valve with 5 ports part # 85123221. Installed 6th air line for trl brake with supplied 2 fittings and 3/8 air line that comes with kit. Same thing. Only way to use both tans is when i apply foot brake and when i apply air with yellow and red knobs. Drop drive air bags or use 5th wheel slider or seat air only uses air from F tank to fill it up. Even now after i get loaded or unloaded from fork lift going in and out of trl only looses air from F tanks. Driving down after 15-20 minutes only looses air from F tank
I dont get this. Why these new valves old or new design doing different than my original valve. Can someone tell me do you loose air from both tanks driving down road

 

Another update. I re installed my original 6 port brake valve. And uses air from both tanks no matter what i do, fill up drive air bags, use seat air, driving down the road. Both gauges from F and R tanks goes up or down when i use air from anything
Im lost

 

Can someone with newer Volvo like 2010+ tell me does gauge from R tank goes up or down while driving and does drive airbags use air from R tank on fill up. 2010 + or maybe even older uses new Bendix valve from the factory and thats why im asking
Thanks

 

Than my factory set up was wrong since day one?

 

Than can someone with Volvo any year from 2004+ confirm this. Any year. Why is so hard to look up darn instrument cluster. Or non of drivers pays attention whats going on with air gauges ?