Hi Srujan,
2 reasons,
1. Might be you have configured with wrong Monitor, choose the correct one and enter proper parameter details for key figure
or the issue with the key figure itself. you can refer the notes 1807734 - ST-A/PI 01Q: Advance Corr. BP Analytics - TBIs for ERP, like this lots of note available, refer bpmon advance correction, make sure you applied.
2. Issue might be with the data collection, below guide might help, http://service.sap.com/~sapdownload/011000358700001186112010E/Troubleshooting_for_BPMon.pdf
Thanks
Jansi