dijkstraPath weight

Hello,
I tried to use dijkstraPath with a weight.
However, when I set an edge attribute as weight, I get an error 'Can not read property' toString 'of undefined'.
How i can use an edge attribute for weight ?

var poidMan1 = parseInt(featureToUpdate.getProperties().ifmanuel);
G.addNodesFrom(geometry);
G.addEdge(
start, end,
{
poidMan: poidMan1,
}
);
path = jsnx.dijkstraPath(G, {source:depart, target:arrivee, weight:poidMan });

Thanks for your help.