TYPO3-Browser: PHP Warning: Invalid argument supplied for foreach()

filter {
	tx_ppreisen_type {
		name < plugin.tx_browser_pi1.displayList.master_templates.category_menu
		name {			
			first_item >
			wrap.title_stdWrap >
			wrap.item.display_hits = 0
			wrap.item.display_without_any_hit = 1
			wrap.item.selected = active
			order.field = value
			order.orderFlag = DESC
		}
	}
	tx_ppreisen_journey {
		startdate < plugin.tx_browser_pi1.displayList.master_templates.category_menu
		startdate {
		first_item >
			wrap.title_stdWrap >
			wrap.item.display_hits = 0
			wrap.item.display_without_any_hit = 1
			wrap.item.selected = active
		 order.field = startdate
			area < plugin.tx_browser_pi1.displayList.master_templates.areas.sample_period
			area.interval.case = month
			area.interval.month.start_period.stdWrap.value = 2011
			area.interval.month.value_stdWrap.strftime = %B %Y
			area.interval.month.times_stdWrap.value = 12
		}
	}
}