No more capturing packets from Wi-Fi

Look, I've got a problem. My computer is MacBook Pro 13/2011. I used wireshark for a long time and everything was perfect. I was catching packets of Wi-Fi, analyzing them. But something changed and now, when I use HTTP protocol filter I can see only m-search which doesn't help me at all. I can see all packets but only of my own computer. Got Mac OS X 10.7.2 , I've installed Windows and tried wireshark there but the result was the same. Can somebody help me please? P.S. I couldn't find the answer to my question, but if it was already asked, please share the link