Who do I find an item lost in an airport?

I left a black ipad mini in LAX airport and filed a report with that specific airport (which cost me 40 bucks) I also called, and the man who answered told me that an item matching my description had not been found, and to file a report with the airline I was traveling with. So I did (it was United Airlines, and it was free) and they said they would update me 2 days later. So two days later they said no items matching my description were found. I filed a second report with United Airlines, and called, but the robot just told me to email them. I would really like to find it, and I just left it on a chair at the gate so it shouldn't have taken very long for someone to give it to lost and found. And suggestions on what to do?

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