SQLException "Connection is closed. Operation is not permitted"

I'm accessing postgres database through tomcat 4.3.1.
I'm able to execute the select and update query through my application
but Insert query is giving following SQLException :
Connection is closed.  Operation is not permitted.

If I execute the same insert query by simple java program using jdbc
connection, It's working. But the same query is giving above exception
in tamcat.

Please help me. Thanx in advance.

following is the ExceptionStackTrace :

IN insert : insert into account(accNo,traderId,dbcNo,bal) values (1,
'rajiv', 1, 5000.0 )
Insertion Failed : Connection is closed.  Operation is not permitted.
Connection is closed.  Operation is not permitted.
    at org.postgresql.jdbc1.AbstractJdbc1Connection.ExecSQL(AbstractJdbc1Connection.java:503)
    at org.postgresql.jdbc1.AbstractJdbc1Statement.execute(AbstractJdbc1Statement.java:320)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:48)
    at org.postgresql.jdbc1.AbstractJdbc1Statement.executeUpdate(AbstractJdbc1Statement.java:197)
    at org.postgresql.jdbc1.AbstractJdbc1Statement.executeUpdate(AbstractJdbc1Statement.java:183)
    at src.DataManager.Insert(DataManager.java:64)
    at src.Bank.createAccount(Bank.java:149)
    at src.Trader.getAccount(Trader.java:314)
    at CreateAccount.doPost(CreateAccount.java:144)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:716)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:809)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:200)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:146)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:209)
    at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:596)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:433)
    at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:948)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:144)
    at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:596)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:433)
    at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:948)
    at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2358)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:133)
    at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:596)
    at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:118)
    at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:594)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:116)
    at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:594)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:433)
    at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:948)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:127)
    at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:596)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:433)
    at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:948)
    at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:152)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:799)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:705)
    at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:577)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
    at java.lang.Thread.run(Thread.java:536)