Ps3 on dual HDMI port monitor

Hi guys, just a question on the ps3 connecting to the PC monitor....

I have a LG E2770 the 27 inch, it has 2 HDMI port and 1 DvI-D and the D-sub

I connected my PC to one of the HDMI port it works

but when i connect my ps3 to the monitor on the second port or the first, it never display on the screen at all...

but on the youtube video say monitor does work on ps3 but i am just confuse on what i am seeing here

Any help will be greatful :D

i did but never work

bump