How to make DFF visible on PO based on BU?

Summary:

We have a requirement where we need to make a DFF Visible and Required on PO Header when the Requisition BU is 'XXXXXX'. Through Sandbox customization, we are trying to achieve this requirement.

We are using the below mentioned expression in DFF "Rendered" field:

#{bindings.ReqBuName.inputValue==XXXXXX}

While doing it even when we click on Test - it returns 'True' value. But when we click on Apply, even though the return value is true, it makes the DFF not visible.

Any help is much appreciated.

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