Different space between columns in Bootstrap

Different space between columns in Bootstrap

I have been spending a lot of time doing my first page in Bootstrap .
Everything was good i did two columns and started third but I couldn't
because i had no place, in fact second span6 I had under span12. I don't
know what's going on because i set 10px space between columns in the
beginning. I will be grateful for your help
http://wstaw.org/h/e0a3aa6f0f7/