Report schedule not executed but no error

[Sunchaser]

Hi all,

On a Cognos 11.1.R3, I saw this morning that a report schedule was not executed, but:

. no error in the run history
. all objects (report, report view, etc..) are valid
. it is possible to run the report manually successfully
. it is possible to run the schedule manually successfully
. no reboot of the server or whatsoever of this kind
. no trace of this report schedule in the "past activities" section
. this schedule has been running daily successfully for years now
. all other schedules have been executed successfully

It looks as if this report schedule has been simply ignored by the system, and I don't know how to understand why.
There was no change on the user / owner of this object. Nevertheless, I did a "renew credential", just in case ...

Any hint to find out what could have happened?
Thanks!
Vinc