The XML is wrong,
<GameModifier>
<ModType>Unit</ModType>
<Attribute>UnlockCombatAbility</Attribute>
<StrVal>SummonAirElementalTactical</StrVal>
<Provides>Allows the caster to Summon an Air Elemental in tactical combat</Provides>
</GameModifier>
vs spelldef
<SpellDef InternalName="SummonAirElemental_Tactical">
mocachild, can you move this topic to the FE support forum? To make sure they see it. Press edit and you can change where the topic is in the rolldown menu.