Duplicate old backup LTO4 - LTO6

Hi,

i need to duplicate old backup on LTO4 to LTO6

I go to menu "catalog"=>"duplicate" right clik and i duplicate to my storage unit LTO6

When i do this, i have this error:

16/11/2017 09:17:02 - begin Duplicate
16/11/2017 09:17:03 - requesting resource XXXXX
16/11/2017 09:17:03 - requesting resource 004363
16/11/2017 09:17:03 - reserving resource 004363
16/11/2017 09:17:03 - Error nbjm(pid=5060) NBU status: 830, EMM status: No drives are available
16/11/2017 09:17:03 - Error nbjm(pid=5060) NBU status: 830, EMM status: No drives are available
16/11/2017 09:17:03 - Error nbjm(pid=5060) NBU status: 830, EMM status: No drives are available
16/11/2017 09:17:03 - Error nbjm(pid=5060) NBU status: 830, EMM status: No drives are available
16/11/2017 09:17:04 - end Duplicate; elapsed time: 0:00:02
No drives are available (2001)

I don't understand:

i have my storage unit with my media in.

I can do backup on the LTO6 or LTO4 media (i try this)

But, i can't duplicate my old backup image.

Thanks.