If no activity was recorded for the current month selected for a report, the report will not show as an option on the OCLC Usage Statistics page. However, if you would like to see multiple months at once, you can open the report from the last month with activity, change the month listed in the Period drop-down menu, and click Update.
More information about available ILL reports on the OCLC Usage Statistics page can be found on the WorldShare Interlibrary Loan help page.