Private Sub Command58_Click()
Forms![frmCustomerInvoice]![Total] = DSum("[ItemPrice]", "qryInvoiceItems", "[InvoiceNo] = Forms![frmCustomerInvoice]![InvoiceNo]")
End Sub

Private Sub ProductId_Change()
Forms![frmCustomerInvoice]![Total] = DSum("[ItemPrice]", "qryInvoiceItems", "[InvoiceNo] = Forms![frmCustomerInvoice]![InvoiceNo]")
End Sub

Private Sub ItemPrice_Exit(Cancel As Integer)
Forms![frmCustomerInvoice]![Total] = DSum("[ItemPrice]", "qryInvoiceItems", "[InvoiceNo] = Forms![frmCustomerInvoice]![InvoiceNo]")
End Sub