Not sure what is causing the error.
CurrentDb.Execute "UPDATE dbo_RootCause SET Part = '" & Me.cboPart & "', Qty = '" & Me.cboQTY & "', Code = '" & Me.cboCode & "', Reason = '" & Me.txtReason & "', RootCause = '" & Me.txtRootCause & "', CorrectiveAction = '" & Me.txtCorrectiveAction & "', CAdate = '" & Me.txtCAdate & "', CA_Comp_By = '" & Me.txtCA_Comp_By & "', ReturnInv = '" & Me.cboReturnInv & "', ReturnCust = '" & Me.cboReturnCust & "', CustFollowUp = '" & Me.cboCustFollowUp & "' WHERE ListItems = " & Me.txtListItems & "", dbSeeChanges