L2J Server

I am working on Hellbound Quest and i have small problem:

<item id="1"><!-- Native -->
<production id="9670" count="1" />
<production id="9671" count="1" />
<production id="9669" count="1" />
<ingredient id="9850" count="1" mantainIngredient="true" />
<ingredient id="9674" count="30" />
</item>

9850 = Basic Caravan Certificate, mantainIngredient is TRUE, but it still consumes certificate.
Any ideas whats wrong?

afaik it's maintain

no, there is a typo, and the code should work with mantainIngredient. check other multisell xml.