Editing the carrying capacity

[Grabarz]

Hello , im back to rimworld after some years and im on stage of editing some values of the mods.

I downloaded EPOE mod - it works fine expect that for some reasons installing Exoskeleton frame or Advanced bionic spine does not gives you additional carrying capacity like i intended to do

I added values like:
      </addedPartProps>
      <stages>
         <li>
            <statOffsets>
               <CarryingCapacity>+50</CarryingCapacity>
            </statOffsets>
         </li>
      </stages>

it shows in the game, under installed body parts but my pawn still can cary just 28kg, not sure why...

For some reason if i mod a apparel mod - for example jacket or trausers and i add same modification it works correctly and now my pawn can carry 78kg instead of 28...

Any idea what im doing wrong?
Here is a complete heddif:
<HediffDef ParentName="addedPartAdvanced">
      <defName>AdvancedBionicSpine</defName>
      <label>advanced bionic spine</label>
      <labelNoun>an advanced bionic spine</labelNoun>
      <description>An installed advanced bionic spine. A biogel nerve bundle runs down an articulated plasteel core, surrounded by a lattice-dust healing system. It is better than a biological spine in almost every way.</description>
      <descriptionHyperlinks><ThingDef>AdvancedBionicSpine</ThingDef></descriptionHyperlinks>
      <spawnThingOnRemoved>AdvancedBionicSpine</spawnThingOnRemoved>
      <addedPartProps>
         <solid>true</solid>
         <partEfficiency>1.5</partEfficiency>
         <betterThanNatural>true</betterThanNatural>
      </addedPartProps>
      <stages>
         <li>
            <statOffsets>
               <CarryingCapacity>+50</CarryingCapacity>
            </statOffsets>
         </li>
      </stages>
   </HediffDef>