It works for me.

Verify the bookmark in the dropdown formfield is named the same as in your Ref field - you made a mistake in the code you showed. Include a tick on Calculate on Exit for that dropdown formfield.

Make progress by testing at each stage
1. Create the field {Ref servicetype} and test it by changing the dropdown and verify that the Ref field updates when you move the cursor from the dropdown.
2. If step one is working as expected, try a simple nested
{IF { REF servicetype } = "SERVICES1" True False}
3. If that shows True or False as you expect, replace the True with your preferred text. Test again
4. Finally, delete the False.

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Andrew Lockton
Chrysalis Design, Melbourne Australia