Thunderbolt doesn't detect external monitor

Hi everyone
i am having trouble connecting my TV to my MBP 15" 2011.
I bought a mini DV to HDMI adaptor from here:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130493628739&ssPageName=ADME:L:OU:US:1123
and when i try to connect it, nothing happens, the thunderbolt port doesn't recognize anything.
I am using gfxCardStatus but also tried to disable it or force the discrete GPU but nothing helps.
I know the adaptor is good, i tried my friend's 2010 MBP and it works.
I am afraid there is a problem with my thunderbolt port, anyone encountered that ?

 

Well, i took it to the local apple representative in my country and it worked in the store, apparently, the adaptor is not thunderbolt compatible.
I saw people here recommending to buy any mini dp to HDMI adaptor, but for the 2011 models one needs to be more careful and buy only the thunderbolt compatibles.