Help needed with calculated trigger based of sum of items

[rrr]

How could I create a trigger, which is based on 3 or more items?

The Item-values are only 0 or 1

Example 1:

({host:item1.sum(60)}+{host:item2.sum(60)}+{host:item3.sum(60)})>3

The trigger never turns true.


Example 2:

{host:item1.sum(60)}+{host:item2.sum(60)}+{host:item3.sum(60)}>3

The trigger turns only true if sum-value of item3 is greater than 3 in the last 60 seconds.


I want a true trigger if the sum is greater than 4, regardless of which item.