I'm trying to use this code to hide a #Error in a form field but the syntax seems to be wrong.
=IIf(IsNull[txtEquipmentN]),"",DLookUp("[Manufactor/EquipmentType]","tblEquipment","[EquipmentID] = " & [Forms]![frmSites]![txtEquipmentN])
In other words if txtEquipmentN is empty on the form, the field using the DLookup should be blank. Otherwise use the DLookup.
1. Correct mapping of your controls to the fields of your Recordsource
2. Your RecordSource so that is not producing #Error...