Hello Christian,
Sorry for no more replies, I have been out of SCN for a couple of weeks.
About your interesting question: "what is the different between command "latest version" and if I use an defined session-id" ? this should be actually addressed to HP Data Protector people 
From ASE point of view ob2syb is just an API that enable communication between Backup Server and HP DP. More simply, parameters used between each "::" are managed by HP Data Protector.
As mentioned Tilman the issue seems to come from HP DP side, so it should be analyzed from that point of view. Not sure how the API backup specification are provided, ie I'm not sure why means the "::000" at the end :
The 'api_read' call failed for database/archive
device while working on stripe device 'ob2syb::<BACKUP Session ID>::<SID A>::<SID A>::000'
Regards,
Victoria.