Hi Minakshi,
Check the exception in the logs.
Check these things also:
1. IDBC Driver is uploaded and deployed in the JDBC Drivers screen.
2. In Server url, <serverName > and <portNo> should be of machine where MS Sql is installed.
Also check the following blog if you need to download the drivers:
Data Connection Details for Data server Configuration
Regards,
Rohit Negi.