need to add the supplier site code as a DFF parameter on the invoice header level

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and i used the below query but its not valid it gives error

we created DFF on invoice header and its value set retrieve bank list from table and we need to restrict this value set to retrieve only the banks related to the supplier site on UI

so i added in the below where condition the last line (AND VENDOR_SITE_CODE = :{VENDOR_SITE_CODE}) in order to restrict the list of banks related to a specific supplier site that existing in UI (binding variable) so any advice in this case please , what's the problem in the below