I am testing the waters with modding and figured I would try something easy. I create a new directory under Mods and copied in both the StarbaseDefs.xml and the StarbaseModuleDefs.xml. I made two changes. First I upped the base hit points to 500:

  <Starbase>
    <InternalName>BasicStarbase</InternalName>
    <DisplayName>BasicStarbaseName</DisplayName>
    <Stats>
      <EffectType>HitPointsCap</EffectType>
      <Target>
        <TargetType>Starbase</TargetType>
      </Target>
      <BonusType>Flat</BonusType>
      <Value>500</Value>
    </Stats>

Then I added a hit point modifier to the first Star base defense system:

  <StarbaseModule>
    <InternalName>StarbaseDefenseSystem</InternalName>
    <DisplayName>StarbaseDefenseSystem_Name</DisplayName>
    <Description>StarbaseDefenseSystem_Dec</Description>
    <ShortDescription>StarbaseDefenseSystem_ShortDec</ShortDescription>
    <Icon>GC3_Starbase_Defense_System.png</Icon>
    <SpecializationType>Generic</SpecializationType>
    <!-- Stats -->
    <Stats>
      <EffectType>ModuleConstructionPoints</EffectType>
      <Scope>Queue</Scope>
      <Target>
        <TargetType>StarbaseModule</TargetType>
      </Target>
      <BonusType>Flat</BonusType>
      <Value>1</Value>
    </Stats>
    <Stats>
      <EffectType>HitPointsCap</EffectType>
      <Target>
        <TargetType>StarbaseModule</TargetType>
      </Target>
      <BonusType>Flat</BonusType>
      <Value>250</Value>
    </Stats>

I started a new game after saving the files and making sure mods were enabled. I created my first star base and the UI only showed 200 hit points. I then created the first star base defense system which in the tool tip showed the +250 hit points, but after building it and waiting a turn, it still shows only 200 hit points. What did I do wrong? Thanks!