set-BEDuplicateStageBackupTask issues

Hi,

I periodicaly have to modify my tape library partitionning and search a way to modify all my duplicate jobs by using scripts.

by example i change my 24 slots library organisation from 10-10-4 to 12-10-2 and need to change the storage destination for my "silver*" jobs :

I've first tried :

GEt-BeBackupDefinition "Silver*" |Set-BEDuplicateStageBackuptask "Tape-*" -storage "ROBOT [0001..0012]" |save-bebackupdefinition

This script correctly change the storage of my jobs but erase mediaset name.

then i do the following :

GEt-BeBackupDefinition "Silver*" |Set-BEDuplicateStageBackuptask "Tape-*" -storage "ROBOT [0001..0012]" -tapestorageMediaset "Week_Silver"|save-bebackupdefinition

but the job have now "keep data for 4 weeks" as mediaset though my "week_silver" appears correctly in get-bemediaset.

is there a proper way to edit my tapeduplicate jobs ? do i miss something with Set-BEDuplicateStageBackuptask ?