Yes, text references are missing. <description>, <Civilopedia>, <Strategy>, <Help> should point to data in a language file. Look at Kael's guide for an example. I'm not sure that's why it doesn't load, though.
Also, here:
Code:
<Unit_Flavors>
<Row>
<UnitType>UNIT_GREEK_HOPLITE</UnitType>
<FlavorType>FLAVOR_OFFENSE</FlavorType>
<Flavor>4</Flavor>
</Row>
<Row>
<UnitType>UNIT_GREEK_HOPLITE</UnitType>
<FlavorType>FLAVOR_DEFENSE</FlavorType>
<Flavor>8</Flavor>
</Row>
</Unit_Flavors>
I guess you forgot to replace the UNIT_GREEK_HOPLITE by UNIT_ANTIMECH
And, why this?
Code:
<Requirements>TXT_KEY_NO_ACTION_SETTLER_SIZE_LIMIT_HARDCODED</Requirements>
It's only used for settlers, and i'm not sure it's correct to use it for units.
Edit: Oops, that's not all. About the promotion:
Code:
<UnitPromotions_UnitClasses>
<Row>
<PromotionType>PROMOTION_ANTIMECH</PromotionType>
<UnitClassType>UNITCLASS_MECH</UnitClassType>
<Modifier>250</Modifier>
</Row>
</UnitPromotions_UnitClasses>
You used UNITCLASS_MECH instead of UNITCLASS_ANTIMECH so it can't work.
And by the way, the AllowEmbark, is probably unnecessary.
Edit2: UnitClasses references are also missing. You *need* this reference for the mod to load anything at all, here's the correct one for your unit:
Code:
<GameData>
<UnitClasses>
<Row>
<Type>UNITCLASS_ANTIMECH</Type>
<Description>TXT_KEY_UNIT_ANTIMECH</Description>
<DefaultUnit>UNIT_ANTIMECH</DefaultUnit>
</Row>
</UnitClasses>
</GameData>
There's probably other things wrong there and there. I'd strongly suggest you to use Kael's guide as a reference and to look at other people's modifications. You should use separate files for units, classes, promotions, and texts. It's not mandatory, but it's good practice and allows easier debugging as one error in one file won't break a whole project.
Also, start small, add a basic unit first, check if it loads correctly. If it does, then add the promotions, and so on. It makes it easier to spot where the issue belongs.