Can someone explain why I can't ask more questions?

When I try to ask - I have notification like this:

"You have reached your question limit"

How can I fix it? I have tried to delete my 0-rating questions, but I still can't create new question.

**Edit:**

I have 4 questions. Two have negative (-1) feedback:

https://superuser.com/questions/814541/differences-between-intel-i7-m-and-u-series

one guy downvoted and nobody else looking at it after I fixed my question by removing sentence about shopping.

Another example:

https://superuser.com/questions/811128/remote-desktop-software-for-gaming-still-nothing-in-2014

So, my average is below zero now, because I didn't asked about anything popular yet. This is not fair.