How can I use conditional formatting in the import format expression field?

The conditional format that I add to the expression field doesn't work. Not sure what the issue is.

Trying to transform source account 21430 to 11111 in the target field.

I am following the example that appears in the conditional format expression help section.

This is the expression that I used in the import format field for Account.

if (Account == "21430") return "11111"

The .dat file fails to process. The error message I receive is "

Integration process completed with warnings".

Version

Service:		Planning and Budgeting Cloud
Application Type:		EPBCS
Version:		24.08.58

Thank you