Regex Evaluation capture group

I can never get the capture groups to work.

Start with something simple:

1) Generate 1 row with 1 field, let's say TEST = "123"
2) Connect to Regex Evaluation step

Create fields to capture groups CHECKED
Field to evaluate: TEST
Regular expression: (.*)

This should capture all into one group. Define the single group as a new field, using String as type.

Result is negative, the capture is <null>. Any help?