Laptop cannot detect HDMI connection to HDTV
I have a HDMI cable with a displayPort adapter connecting laptop and a Panasonic HDTV. The cable works perfectly with one laptop (IBM Thinkpad with a Radeo Mobile Video card) by displaying videos/screens on the TV, however it does not work with an HP Probook 6550b with an Intel HD Graphics and displayPort as well. The HP does not see the HDMI connection at all. I did notice a flashing laptop screen when I was connecting/disconnecting the cable from the laptop, meaning it was able to detect something.
I have tried to google for all possibilities but failed to find any answers and hope experts at this forum could shed some lights on the issue.
Thanks a lot.