I created my first BRS Rule (using XSD) in BizTalk Server Business Rules Composer and deployed it.
After browsing for some time, I find that it happened because, the Document Type Property for the Schema in the Facts Explorer (shown above) is different from the Fully Qualified name of the Actual Schema in the BizTalk Project
The issue is that, in the beginning, Call Rules shape was not able to find any matching Message to the Schema which is deployed with the Rule.
Since I modified the schema in BRE with the Fully Qualified Name of the BizTalk solution, it found a matching message and displayed in the Call Rules Shape.
Hope it is useful..