As You can see on below screen specifics information for database aren’t available.
How to resolve
Check that job SAP_COLLECTOR_FOR_PERFMONITOR (report RSCOLL00) is running via transaction code SM37. You can schedule the job to be run hourly (as per SAP recommendation) via transaction code SM36.
Next we have to refresh all datasets. Simply, run transaction DB02 and click F8 – this will trigger job name: REFRESH SPACE STATISTIC:DEFAULT. When this job ended you will be able to observe fresh data: