lubuntu live usb not working in laptop.

Hi guys,

I have been trying to install lubuntu (last version) in an old laptop withouth succes. The BIOS does not recognize the usb drive to boot from it. I tried in a hp stream 2 with the same problems, wich I don't understand since I had lubuntu installed in this one some time ago.
I have tried with different usb drives with the same problem. I have tried other linux distributions and versions and Ubuntu is the only one that boots. The lubuntu live usb is not the problem because it works in my desktop PC.
I have tried to bu the usb with unetbootin, startup disk creator, linux live usb creator , ... I don't think that's the problem either.
Do you know what can be the problem, or if there is another way to force the laptop to boot from the usb?

Thanks.