Global Mapper v25.0

Problem with creating a custom datum transformation


I am using Geographic Calculator 2023. I want to create a custom datum transformation Afgooye to WGS. To do this, I first copy the available transformation, and then edit it like this:

I'm saving a new transformation(XML). When I reopen the Geographic Calculator, I see that the Datum Transforms are saved, but the area of ​​use remained the same as that of the original transformation.

Tell me, please, what is my mistake?

Thank you!