Unexpected behaviour of dashboard's surveillance view

The surveillance view shows an unexpected behaviour. Even though there are some services down and the corresponding table cell is colored red, it shows 0 of XX services down (see screenshot).

I'm using the following configuration for the surveillance view "default":

<view name="default" refresh-seconds="300" >
<rows>
<row-def label="IBM1" >
<category name="IBM1"/>
</row-def>
<row-def label="IBM2" >
<category name="IBM2" />
</row-def>
<row-def label="Dienste" >
<category name="dienste" />
</row-def>
</rows>
<columns>
<column-def label="Status" >
<category name="everything" />
</column-def>
</columns>
</view>

As our infrastructure is not clearly divided in production, testing and development, I changed the view a bit. Every node automatically gets the Surveillance Category "everything" assigned.