Problem with my code

I'm most likely trying something that's impossible again, but I'd like to run it by the more knowledgeable fellows of the forum before giving up on my ideas. The big idea was to make a bloodtype that increases attack by 1 each level and reduces defense by 2. In the current code there's also a line about HP, but that was just for testing purposes.

Code: xml
<AbilityBonus InternalName="Blood_BarbarianAbility">
 <AbilityBonusOption InternalName="Blood_Barbarian">
 <DisplayName>Barbarian Blood</DisplayName>
 <Description>+ 1 HP per level,+ 1 Attack per level, -2 Defense per level</Description>
 <Icon>RoundCrest_11.png</Icon>
 <GameModifier>
 <Type>Unit</Type>
 <Attribute>AdjustUnitStat</Attribute>
 <StrVal>UnitStat_HitPoints</StrVal>
 <Value>1</Value>
 <PerLevel>1</PerLevel>
 <Provides>+1 HP per level</Provides>
 </GameModifier>
 <GameModifier>
 <Type>Unit</Type>
 <Attribute>AdjustUnitStat</Attribute>
 <StrVal>UnitStat_Attack_Pierce</StrVal>
 <Value>1</Value>
 <PerLevel>1</PerLevel>
 <Provides>+1 Attack per level</Provides>
 </GameModifier>
 <GameModifier>
 <Type>Unit</Type>
 <Attribute>AdjustUnitStat</Attribute>
 <StrVal>UnitStat_Defense_Pierce</StrVal>
 <Value>-2</Value>
 <PerLevel>1</PerLevel>
 <Provides>-2 Defense per level</Provides>
 </GameModifier>
 <AIData AIPersonality="AI_General">
 <AIPriority>5</AIPriority>
 </AIData>
 </AbilityBonusOption>
</AbilityBonus>