Hi @Chua Liang Wei ,
You have most likely the wrong target in your reports, this is fairly common, I suggest you have a look at these links:
Why do my SCOM reports show no data?
https://kevinholman.com/2008/04/21/why-do-my-scom-reports-show-no-data
SCOM Reporting series – Why is my report empty?
https://blog.topqore.com/scom-reporting-series-why-is-my-report-empty/
Troubleshoot blank reports in System Center Operations Manager
https://learn.microsoft.com/en-us/troubleshoot/system-center/scom/troubleshoot-blank-reports
Here's also an old TechNet forum thread discussing this:
Blank Performance Details Reports
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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Best regards,
Leon