服务器为tomcat 5.0.29,现在我在conf/server.xml配置了数据源（JDBC-ODBC和sqlserver驱动都试过了）,然后通过JDNI来查找数据源，但总是出错，出错信息如下，请各位大虾帮助分析一下是什么原因：
javax.servlet.ServletException: Cannot create JDBC driver of class “””” for connect URL “”jdbc:odbc:db””
org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:845)
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:778)
org.apache.jsp.test_jsp._jspService(test_jsp.java:60)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

root cause 

org.apache.commons.dbcp.SQLNestedException: Cannot create JDBC driver of class “””” for connect URL “”jdbc:odbc:db””
org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:780)
org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:540)
util.DatabaseConn.getConnection(DatabaseConn.java:13)
org.apache.jsp.test_jsp._jspService(test_jsp.java:48)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)