Lenovo Thinkpad T520 doesn't boot from Ubuntu 15.10 Installation USB Stick

I'm trying to install Ubuntu 15.10 from my Intenso 32GB USB-stick on my Lenovo Thinkpad T520.

I created a USB-Stick with the tool linked at http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-windows.

I choose to format the USB-Stick with Fat32.

I cound't verify that the USB-stick was built successfully, since I'm not able to boot from USB with my other Laptop either, but I don't see any reason why it shouldn't have been be created successfully.

I can't select the USB-stick from the BIOS boot-menu, so I think that's the problem. Changing the boot-priority of USB-HDD USB-CD etc. didn't help with booting either.

I already read ThinkPad T520 won't boot from USB. As I understood it, his problem was the type of usb-stick or the brand. I don't know if my usb-stick is compatible with my bios and I also don't know how I can find it out either.

Thank you for your help!