How to solve "ORA-12514: TNS:listener does not currently know of service requested in connect descriptor" error?
I do not have any clear explanation for this problem solution. However I used SID instead of service name in connection string and it worked.

Edit: A service name is more flexible than a SID would be. A database can dynamically register with a listener using one or more service names. In fact, more than one database can register with a listener using the same service name.A database on the other hand has a single SID. And a single SID goes to a single database. So I would say it is safe to use SID rather than service name.