[igraph] problems with edges

[Figa Pelosa]

Hallo everybody, I hope you could help me with my problem.
I'm working with python and I'm exploring igraph for the 1st time..
I do not really understand how to address the edges.

Here's what I do:
1) I read a adjacency matrix from a text file with:
g = load('./myGraph.txt')
g.to_undirected(collapse=True)

where the text file looks like this:
0 1 2 3
1 0 4 5
2 4 0 6
3 5 6 0

2) I now want to check the weight of the edge connecting vertex number 0 to vertex number 1, which should be 1.. so I write:
g.get_eid(0,1)

but it returns 0.

Why is it so?
I hope you can help me
Thanks a lot
F