Netbackup & Bad file number (9)

Hello together,

we have here an problem with Netbackup on Sun Solaris.
We want backup an Oracle DB, with 2 Streams, the first Stream works
correctly an come back with successfuly message, the second Stream
come with error:

03:06:56.756 [2983] 16 writeToServer: ERR - send() to server on
socket failed: Bad file number (9)
03:06:56.756 [2983] 16 writeTarHeader: ERR - cannot write image tar
header to DATA socket
03:06:56.756 [2983] 16 handshake: ERR - writeTarHeader() failed
03:06:56.756 [2983] 16 CreateNewImage: ERR - handshake() failed
03:06:56.757 [2983] 16 do_backup_resto Failed to open.
03:06:56.757 [2983] 16 sbtbackup: Failed to open for backup.

back.

Have anybody an idea, what we can do, to eliminate this problem.

Thanks for your help.
Regards
Wolfgang