Subreport using db2 server - Help please

Hello,

I need help with a subreport connection. I have a main report using a different data source, and am trying to connect via connection expression as follows :

java.sql.DriverManager.getConnection("jdbc:db2://hostname/db", "username", "password")

When I am in jaspersoft studio, it seems to work, at least the query functions... However, from Clarity Advanced Report I keep getting : 

"Error when evaluation expression: java.sql.DriverManager.getConnection("jdbc:db2://hostname/db", "username", "password")"

I really need to get this worked out, as I have used something similar in the past... not sure why this is not working in Clarity.

Thank you!