I'm trying to migrate some users from a zimbra open source server to zimbra network edition.

Following this post about the subject: ZCS-to-ZCS Migrations » Zimbra :: Blog

I should be able to use this command to export a mailbox from the open source server:
/opt/zimbra/bin/zmmailbox -z -m user@domain.com getRestURL “//?fmt=tgz” > /tmp/account.tgz

When using trying that I get this error:
ERROR: service.FAILURE (system failure: GET from https://zimbra.url.com:443/home/user....com/.?fmt=tgz. failed, status=501. not implemented yet)

How can i fix this? When i'm logged in on the user with web interface I can get the .tgz file of the user without a problem with this url:
http:// server.domain.com/home/user/?fmt=tgz

Need to do it from CLI because of automation.

Thanks in advance