usb key format

I have repeatedly tried this command: # dd if=/dev/zero of=/dev/da0 bs=2048 Dolphin automatically mounts the USB. I could also work by mounting the device on a directory, could delete the files. The DD command is to format the device to transfer the install image. The DD command didn't work...

Hello everyone. I'm posting my question here, following the suggestion of Balanga. I try to format a 256GB Lexar USB key in FreeBSD (with KDE), GPT with UFS, unsuccessfully. The key does not show up. I don't understand why. Maybe you'll have an idea ? Here is everything I did : gpart destroy...