field transformation not cpaturing anything

[aviadr1]

I am trying the field tranformation feature. using the "Manager » Fields » Field transformations" UI
I have defined the following transformation
regex=(?.)
key=_raw
format=

now I'm searching for aviad=* in search app and no event comes up. what gives?

[woodcock]

You did not provide any field naming/mapping; try this:

regex=(?.) key=_raw format=aviad::$1