DLO Incremental PST backup error MAPI

- DLO 7.6

- Outlook 2010

Enable incremental backup of PST; i have this error:

Backup - d:\xxx\xxx.com.pst\Drafts\000000005CA9FC64574ED0419388C23C3E89B0A0249C3300 - Mapi resource error.  This could be a network, disk space, or out of memory problem.  Retry the operation. (8004010f) (MAPI_E_NOT_FOUND ) 

Local and Network space is enough, LAN Network is OK.

Any idea about this problem?