You don't need "def $organisation_ids=array()", but only "$orrganisation_ids=$node.data_map.organisation_type.content", You can't define the same variable name twice, see the docs: http://doc.ez.no/eZ-Publish/Technical-manual/4.x/Reference/Template-functions/Variables/def and you don't need to tell ez publish it is an array, it already knows.
Then, the if-statement should be "if $organisation_ids|contains ($option.id)"
