Hi Sai,
Uncheck the option "Supress multiple alerts" for the alert rule on RWB.
Also check alert inbox and run the report SXMSALERT_LOGREADER and check if your alert is present in it.
Go through the blog:
http://scn.sap.com/community/pi-and-soa-middleware/blog/2005/09/09/xi-alerts--troubleshooting-guide
Regards,
Pranav