[mothered]

I think it is the problem of his network card have to be for wireless internet.

As per my post above:

Stating the obvious, Is your network card/wireless adapter compatible?

That's one possibility, there's a few others as already stated.

yes correct. but I think aircrack-ng is not a bad program at all.

I haven't used It In a while but personally, I've had no Issues with the tool.