The following errors are displayed in the backup log when backing up SQL Server .ldf files:
Skipping an included file '....ldf' ( File not found)
The SQL Server database 'xxx' backup failed
There were errors while scanning entries to back up
Any leading spaces (e.g. " MyDatabase.ldf") in database file names are trimmed off by VSS when the file is read. This causes a conflict between the file found by the Agent and the file read by VSS.
Since there is currently no programmatic solution, we recommend that you detach the database with the name that contains leading spaces, then re-import the data to a database with a name that does not contain any leading spaces.