Sierra USB Boot Disk creating failed

Hi, I am desperate already. I have tried everything. I have included every sudo in Terminal or tried to use disk Maker etc. Nothing works. I even used 2 different USB sticks and formatted to every version etc.

Disk Creator says:

An error occurred. Try ejecting the destination disk and reinserting it, it probably couldn't be unmounted to erase it.

Disk Maker X6 says: "erasing drive '/Volumes/UNTITLED'..." does not understand the message <<event sysonotf>>

Terminal

After putting the command in Terminal the Terminals asks for a password - after typing in the passwort nothing happens - just as it was before.

I really dont know what to do. I cannot be the only one with this problem.

Does someone have a solution?

Thanks, Daniel