Headlight issue

Hi everyone, I own a 2008 IS 250. My passenger side headlight is not working. My dad checked the fuses and told me we should just replace the entire assembly. He removed the bumper cover to gain access (per you tube). removed the old assembly and installed new one. Tested it and still did not work. He unplugged the DS light which still works and plugged the new one in and it came on. He did the same thing to the old light and it too came on. What should he do next. I read other post but they dealt with ballast and replacement bulbs.
Any suggestions would be appreciated. I am heading out and will return in about 2 hours, but will check my cell phone to answer any questions.

Thank you,