I have the error #Name? in a form in Access 2013 in a textbox that have as origin a DlookUp function.
Specifically I need to do the same thing that is on this topic: automatically update the field Costo Unitario field based on the selection of the field Operatore

The combobox of the Operatore field takes the values from a table named Operatori that it is like that:
Operatore CostoOp_Unitario
--------- --------
Marco 20,07
Giuseppe 20,02
Gennaro 19,69
Pierangelo 17,05
The function that is set up as Control Source for the textbox that gives the #Name? error is:
=DLookUp([CostoOp_Unitario];[Operatori];"[Operatore]=""" & [OperatoreComboBox].[Text] & """")
based on the function that is present in the thread that I linked above. OperatoreComboBox is the combobox Operatore in the image. Why it outputs this error?