[TYPO3-mvc] Iterator + check modulo

[Dawid Pacholczyk]

Hello List,
  I`m tring to display something after checking the iterator. So I have

<f:for each="{categories}" as="cat" iteration="iterator">
<f:if condition="{iterator.index} % 4 == 0">
display me
</f:if>
</f:for>

but it doesn`t work. What am I missing ?