Cannot execute incremental backup

I have Backup Exec 15. And trying execute incremental backup of Exchange 2010 mailbox database.

I cannot execute incremental backup. Job finished with error (translated from Russian):

V-79-57344-65193 - The selected backup element "\\MAIL-MBX.MOSCOW.SOVMORTRANS.COM\Microsoft Information Store\Sovmortrans mdb" didn't manage to be processed for use in technology of selective restoration (GRT). In case of recovery of the database there was an error "*Null *". Restoration of separate elements won't be available to this selected element of backup

and

Final error: 0xe000fea9 - In runtime of operation in the data store of Backup Exec there was a failure. Additional information is provided in log of jobs.
Final category of an error: HEX

For receiving detailed data on this error follow the link V-79-57344-65193

 

But Full backup finished successfully.

What's the problem?