vertica scala fail

vertica.scala

    import org.apache.spark.rdd.JdbcRDD
    import java.sql.{Connection, DriverManager, ResultSet}

    classOf[com.vertica.jdbc.Driver]
    println("com.vertica.jdbc.Driver loaded successfully ")

    val conn_str = "jdbc:vertica://172.16.251.171:5433/analyticsdb?user=dbadmin&password=analytics"
//    val conn = DriverManager.getConnection(conn_str)

    println("Connection with vertica established ")
    val myRDD = new JdbcRDD( sc, () => 
        DriverManager.getConnection(conn_str),
        "select ROLE_NAME from ROLE_TB WHERE ROLE_ID > ? AND ROLE_ID",
        0, 10, 2, r => r.getString("ROLE_NAME"))