help with block code

[grrmisfit]

Tring to make unbreakable block, but having some issues. Ive done this twice now with cement block and vault door but now im trying to do iron ladder and im getting NRE object reference not set blah blah. Code below, thanks for the help.

<block id="1656" name="AdminFence">
<property name="Extends" value="corrugatedMetalNoUpgradeMaster" param1="DescriptionKey"/>
<property name="MaxDamage" value="500"/>
<property name="Class" value="Ladder"/>
<property name="CustomIcon" value="ladderMetal" />
<property name="Shape" value="New"/>
<property name="LightOpacity" value="0"/>
<property name="Model" value="ladder_round"/>
<property name="Texture" value="446"/>
<property name="UseGlobalUV" value="Local"/>
<property name="ImposterDontBlock" value="true"/>
<property name="Place" value="TowardsPlacerInverted"/>
<property name="ImposterExclude" value="true"/>
<property name="Group" value="Building"/>
<property name="EconomicValue" value="30"/>
<property name="DowngradeBlock" value="AdminFence"/>
<property class="UpgradeBlock">
	<property name="ToBlock" value="ladderMetal"/>
	<property name="Item" value="AdminTool"/>
	<property name="ItemCount" value="1"/>
	<property name="UpgradeHitCount" value="1"/>
</property>
</block>

 

[jk958]

<property name="Item" value="Admin Tool"/>

<property name="ItemCount" value="0"/>

works.