Form Personalization : UPDATE ALLOWED :FALSE

The requirment is to restrict Libiality code field against updatation , once the invoice validated. The libiality code field is hidden in the form means from show field we have to select that for display. I tried with personalizations on the field as follows :

Go to the Invoice Form with querry one of the invoice :Navigation : Help > Digonostics > Custom Code > Personalize

Condition
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Trigger Event : WHEN-NEW-ITEM-INSTANCE
Trigger Object : INV_SUM_FOLDER.APPROVAL_STATUS_DISPLAY
Condition : ${item.inv_sum_folder.approval_status_display.value} ='Validated'
Note : We can use IN operator in Condition like
${item.inv_sum_folder.approval_status_display.value} in ('Validated','Never Validated')
Processing Mode : Both

Action
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Type : Property
Language : All

Object Type : Item
Target Object : INV_SUM_FOLDER.LIABILITY_ACCOUNT
Property Name : UPDATE_ALLOWED (ITEM-INSTANCE)
Value : False

Thanks & Regards,
Kamlesh Nikhade.