Backup on Backblaze B2 don't work on CentoS 6.8 (error : UnsupportedBackendScheme)

[Gilbert Reims]

Hi,
As I see on internet, if I want to use the last version of Duplicity with a VPS server on CentOS 6.8 (or 6.x) I need to install it manually with all dependencies.

I follow this tutorial :
http://blog.helge.net/2014/02/how-to-install-duplicity-on-centos.html
or
http://clients.microtronix-tech.com/knowledgebase.php?action=displayarticle&id=5

It works and Duplicity works fine with FTP backup, and seems to work with all functions.

If I try to use Duplicity with backblaze 2, I have this error message when I launch a .sh script :
UnsupportedBackendScheme: scheme not supported in url: b2://xxxxx:xxxxx@xxxx/xxxx/

But on another VPS with CentOS Linux release 7.2.1511, it works with B2.

On the 2 servers I have Duplicity 0.7.10.

Do you have an idea of the problem ? Maybe I need to add another dependencies ?
Thank you in advance for your answers,
Regards, Gilbert
Sorry if i need to ask question instead report a bug !