Problem with regex in text Mapping

[pico977]

Hi, I am making a panel and I need to change the label text of a connector. I made the model with draft.io, and the label is set with the text "GE":

<mxCell id="myID_10" value="GE" ...

So I made a rule to change the content of the label, and this works. The value represented in the label can be negative or positive, and I want the connector color to change based on the sign. I configured a threshold with condition "value" set to "/.-./" and then I configured the "color mapping" and this also works fine. The last step is to represent the absolute value of the number in the label. I thought about using the "Label / text Mappings" function:

WHAT: myID_10 WHEN: When Metric Displayed HOW: Substring WITH: /[^-]/

But this doesn't work! Do you have any suggestions?