求教JBUILDER连接MYSQL问题!java.sql.SQLException: No suitable driver

小弟为JAVA新手,在做一个帐户管理练习项目,使用Jbuilder2006+Mysql5.0
最新版的connetor-j已经加载好,在Jbuilder及命令提示符下分别用自己写的小程序测试过,连接MYSQL都没问题,能顺利读写,在Jbuilder的databasepilot也能进入目标数据库.
我的项目里我建了一个类来管理连接
public class cardConnect {
    private static cardConnect dbconn = new cardConnect();
    public cardConnect() {
                    try{
                     Class.forName("com.mysql.jdbc.Driver");
                    }
                    catch(ClassNotFoundException ee){ }
          }          public static Connection getconn() throws Exception{                String url= "jdbc:mysql://localhost:3306/credit_card";
                    String username= "root";
                    String password= "";
                    return DriverManager.getConnection(url,username,password);
          }          public static void close(ResultSet rs){
                    try{
                      rs.close();
                    }
                    catch(Exception ex){
                    }
          }          public static void close(Statement stmt){
                    try{
                      stmt.close();
                    }
                    catch(Exception ex){
                    }
          }          public static void close(Connection conn){
                    try{
                      conn.close();
                    }
                   catch(Exception ex){
                    }
          }}来负责连接,可是在我在JBUILDER里面RUN PROJECT的时候却显示java.sql.SQLException: No suitable driver
at java.sql.DriverManager.getConnection(DriverManager.java:545)
at java.sql.DriverManager.getConnection(DriverManager.java:171)
at creditcard.cardConnect.getconn(cardConnect.java:31)
at creditcard.loginFrame.jbInit(loginFrame.java:113)
at creditcard.loginFrame.<init>(loginFrame.java:60)
at creditcard.credicard.<init>(credicard.java:27)
at creditcard.credicard$1.run(credicard.java:65)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)
程序无法执行,也连不上数据库,请问各位高手是怎么回事呢?JDBC已经配置好了啊,
CLASSPATH已经设置好,JAR文件也添加到LIB里面了?谢谢赐教,弄了我好几晚都没弄好,郁闷啊