Moving a image but not the mask!

I’m trying to make a simple game, I want to move a image from down to up, with a mask, I use a transition but the mask is move with the image!!!

[lua]

local tmp, mascara

tmp  = display.newImageRect( actores, ‘toy.png’, 80, 140 )
tmp.x = tablaPosiciones[posicion].x

tmp.y = tablaPosiciones[posicion].y

mascara  = graphics.newMask(‘toymask.jpg’)
tmp:setMask( mascara )
timer.performWithDelay( 500, transition.to( tmp, {time=2500, maskY = tablaPosiciones[posicion].y , y = tablaPosiciones[posicion].y - 60 }), 1 )

[/lua]

Finally I used containers to apply mask in a portion of screen, thanks!

Finally I used containers to apply mask in a portion of screen, thanks!