CollabNet SVN won't dump a repository

For an unknown reason, Collabnet SVN will not dump some of my the repositories, although the others it dumps correctly. The problem is observed with both manual dumps via Repositories->Dump and automatic ones via Repositories->Backup Schedule. In both cases, the job appears under Finished Background Jobs with a zero execution time—the Started at and Finished at fields are the same.

Why can this happen? The affected repositories are not empty, contain revisions, and I am not specifying any specific range on the dump page, expecting SVN to dump it entire. A manual invocation of svnadmin dump works well, but I should like to use the backup scheduler available through the web-interface instead of writing my own.

Mark Phippard of the SVN forums suggested that I check the console log, where I found the following:

WARN admin.RepoDumpJob - Backup skipped: A backup for
repo 'ProjectsNew' is already running, as indicated by
prior existence of progress log
'C:\csvn\data\log​s\temp\job-progres​s-ProjectsNew-dump.l​og'

Deleting that file solved the problem, but I still bear a grudge against SvnEdge for forcing the user to rummage in messy log files instead of reporting the error where the user gave the command—that is in the web interface.