Error with ODBC Connection

I am getting error as below:
ERROR [IM002] [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified
I have installed the ODBC driver to connect to SQL server.
and i am trying to access my database.

connectionString ="Driver ={ ODBC Driver 11 for SQL Server}; DSN = VUM; Server = servername;Trusted_Connection = Yes;Database = databasename;";

what is the solution for issue.