Floating on few blocks in wide content space

[S0OO0]

For my current project, i have to float few blocks to the left. My content block is 720px wide, while the blocks in are 350px width. But somewhy they arent floating each other. SOme of them does, some not. To each block i added rule float:left. I would float them with my hand, but i dont know the order of blocks, so cant predict how will it looks;Here is screenshot of how does it looks now: http://d.pr/i/OKpc