Just giving us Job Details with no information about the client or the type of data does not help.
Status 156 is a generic snapshot error.
What type of data are you trying to backup?
Is the client configured for Microsoft VSS backup?
Is there sufficient space on the client for VSS snapshots?
Have you checked logs on the client ?
Firstly - OS Event Viewer logs - look for VSS errors at backup time.
Next, bpfis log under <install-path>\veritas\netbackup\logs. bpfis log does not exist by default, it needs to be created.