I don't know what or why i can't
If your looking for how to hack Wi-Fi, you might look into this series.
Hi and welcome, you've landed on the right place, you just need to be more specific on your needs, and address your question on the search box first.
This forum has already all it takes to crack almost any type of wifi, but if you believe you have a problem that hasn't been covered yet, feel free to ask. Just be specific stating what is your tatget and what is your attacking machine setup (os + network card etc..).
so go to search box and type wireless hacking then choose what you are going to hack.