Spot welding pressure

Hello .
Im using i have two 2000ic-210f robots which are equiped with ARO spot welders .
Controler R-30ib
Servo in gun is Fanuc.

i have problem with pressure , when i use instruction as SPOT or TD press i have to pick number of pressure from schedule but no matter which pressure i use Robot just uses whatever pressure he likes it doesnt even have to be in schedule and when i lower thickness it just presses lot more. I use Tecna measering tool its very precise but the values are not even close to inputed values.

Thank you for any help.

I dont know what standard do you mean . Yes pressure calibration is done correctly

SEAN-DUDE it shows lets say if schedule is 1500nwt it shows 1490nwt it looks correct and my measrment tool shows about 1350 nwt . But it shows only for second then the value drops to about 500 nwt.

I dont think its tunnig or calibration problem i was able to fix this problem but when i manualy changed caps it happend again. I think its something with WD macros .