Sumar varios lotes de un producto

[soy_nicanor]

Código SQL:

SELECT articulo.articulo, 
(productos.stockTotal) AS stockTOTAL, SUM(lote.stock) AS cantidadLote 
FROM articulo
INNER JOIN productos AS productos ON productos.id_art= articulo.id_art
INNER JOIN lote AS lote ON lote.id_art= articulo.id_art
WHERE 'stockTOTAL' != 'cantidadLote' GROUP BY lote.id_art