[OH3] Time Item State Discription

Via UI i created an item from an iCalender Thing. I get an date time item - Timestamp -. If there is no event i get null or UNDEF. I created a map file show this:

UNDEF=KEINE
null=KEINE
-=KEINE
=KEINE

But that doesn’t work. I don’t get any transformation. It stay as UNDEF in UI.