Dear Siva
You can check a few things on this. Make sure the system dsn you are using matches the service name for the database in the NSA. If this matches and you are on a 64 bit server make sure you are using the 32 bit ODBC connection. A way to test this out is to open the designer tool that comes with Business Objects, when it opens there should be a wizard that starts, go to begin and on the next screen there should be a "select database connection" section under this pick the CA_CLarity drop down option, and below that click the test button. This will tell you if you have a good DB connection with the clarity DB.
Jon Cangson
CA Clarity Support