Guardian Angel doesn't work properly

My Act 2 Mercenary 94lvl has +176 to all res without body armor but with Insght + Tal Rasha’s Helm. In the Mercenary’s menu ( Hell ) it indicates +75 to all res, then i put on him
Guardian Angel Armor (+15 to all max res) and menu bar indicates +76 instead +90 to All Res.
Is it bug?

176 all resist → 76 in hell (-100 penality)
GA Armor upgrade the limit but do not add resistance by itself.
Your merc has 76 (176-100) and if you are able to add more resistances can go up to 90

Hi, as i know 75 is maximum and should be upgraded. In my case it is 76 (bigger then 75). What is wrong?

So…the +15 to all max resistances means that wearing the armor you are able to stack up to 90(75+15) resist, not adding 15res all. Different affixes.
You having 76 max resist in hell, when equipping the armor and raising the res cap, it will say 76. If you add additional res, it will keep on showing until the new cap of 90.

Finally i got it. It is just increasing of diapason without adding any res.
Thanks for explanation.