Did you check "scheduled" on the custom report you created? Only if you did so you will be able to see it in the calendar, and only for the days while "scheduled" was enabled your reports will be browsable.
If that is not the case, please share a screenshot or explain it a bit better, I am not sure I understand your question fully :)
I believe this is letting you know those are the oldest available logs. As the logging rolls over for available space the data is no longer available for reporting.
Click Accept as Solution to acknowledge that the answer to your question has been provided.
The button appears next to the replies on topics you’ve started. The member who gave the solution and all future visitors to this topic will appreciate it!
These simple actions take just seconds of your time, but go a long way in showing appreciation for community members and the LIVEcommunity as a whole!
The LIVEcommunity thanks you for your participation!