Exception in dataSource lookup

HI,

I get Exception in dataSource lookup everytime in my code. How to solve this problem.

I use java,tomcat and sql server

ERROR [ajp-apr-8009-exec-9] 08:37:18,898 com.general.EditBean - Exception in dataSource lookup.
java.sql.SQLException: Exception in dataSource lookup.
    at com.dbmodel.DSUtil.getConnection(DSUtil.java:41)
    at com.dbmodel.DSUtil.getConnection(DSUtil.java:49)
    at com.general.EditBean.getEditRecord(EditBean.java:91)
    at org.apache.jsp.lr.blendedtrainingplan_jsp._jspService(blendedtrainingplan_jsp.java:873)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at com.upside.lms.servlets.GlobalFilter.doFilter(GlobalFilter.java:54)
    at com.upside.lms.servlets.GlobalFilter.doFilter(GlobalFilter.java:38)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:208)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at com.googlecode.psiprobe.Tomcat60AgentValve.invoke(Tomcat60AgentValve.java:30)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.ajp.AjpAprProcessor.process(AjpAprProcessor.java:197)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1812)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)
Caused by: javax.naming.NameNotFoundException: Name [null] is not bound in this Context. Unable to find [null].
    at org.apache.naming.NamingContext.lookup(NamingContext.java:820)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:154)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:831)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:154)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:831)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:168)
    at org.apache.naming.SelectorContext.lookup(SelectorContext.java:158)
    at javax.naming.InitialContext.lookup(InitialContext.java:411)
    at com.dbmodel.DSUtil.getConnection(DSUtil.java:39)
    ... 30 more