Create install media for High Sierra

I have the HighSierra.app in my application folder and I used this command in terminal :

sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

I renamed my usb key MyVolume and it is formated in Mac OS extended jounaled.

I get this error :

Ready to start.

To continue we need to erase the volume at /Volumes/MyVolume.

If you wish to continue type (Y) then press return: y

Erasing Disk: 0%... 10%...

Error erasing disk error number (-69888, 0)

A error occurred erasing the disk.

What is wrong ? Thanks for your help.