Help!! Error in Connecting Informix using JDBC!

i have written the following code with JBuilder, and it works well with Tomcat, but it cannot be run if i place it into some
existing application of WAS, can any1 help me?
package untitled25;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.sql.*;
public class Servlet1 extends HttpServlet {
private static final String CONTENT_TYPE = "text/html";
/**Initialize global variables*/
public void init() throws ServletException {
}
/**Process the HTTP Get request*/
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType(CONTENT_TYPE);
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head><title>Servlet1</title></head>");
out.println("<body>");
out.println("
The servlet has received a GET. This is the reply.
");
jdbcConn(out);
out.println("</body></html>");
}
public void jdbcConn(PrintWriter out)
{
String cmd = null;
int rc;
Connection conn = null;
String newURL = "jdbc:informix-sqli:";
newURL = newURL + "//157.168.136.20:15260/stores:informixserver=hkgrs010_ol1;";
newURL = newURL + "user=informix;password=informix";
out.println("Connection starting....");
try
{
Class.forName("com.informix.jdbc.IfxDriver");
}
catch(Exception e)
{
System.out.println("ERROR: failed to load informix JDBC driver.");
e.printStackTrace();
}
try
{
conn = DriverManager.getConnection(newURL,"informix","informix");
}
catch (SQLException e)
{
System.out.println("ERROR: failed to connect!");
e.printStackTrace();
}
try
{
Statement stmt = conn.createStatement();
cmd = "select * from location";
ResultSet rs = stmt.executeQuery(cmd);
int i = 0;
out.println("location_id,loc_type");
while(rs.next())
{
String value1 = rs.getString("location_id");
String value2 = rs.getString("loc_type");
out.println("
row " + i + " : " + value1 + value2 + "
");
i++;
}
rs.close();
stmt.close();
}
catch(SQLException e)
{
System.out.println("ERROR: execution failed - statment: " + cmd);
System.out.println("ERROR: " + e.getMessage());
e.printStackTrace();

}
}
public void destroy() {
}
}

and the following is the error i got:
An Error Occurred While Processing Your Request...
The following error has been detected:

com.ibm.servlet.engine.webapp.WebAppErrorReport:
Full Stack Trace:

com.ibm.servlet.engine.webapp.WebAppErrorReport:
at com.ibm.servlet.engine.webapp.WebApp.sendError(WebApp.java:542)
at com.ibm.servlet.engine.srt.WebAppInvoker.doForward(WebAppInvoker.java:92)
at com.ibm.servlet.engine.srt.WebAppInvoker.handleInvocationHook(WebAppInvoker.java:123)
at com.ibm.servlet.engine.invocation.CachedInvocation.handleInvocation(CachedInvocation.java:67)
at com.ibm.servlet.engine.invocation.CacheableInvocationContext.invoke(CacheableInvocationContext.java:106)
at com.ibm.servlet.engine.srp.ServletRequestProcessor.dispatchByURI(ServletRequestProcessor.java:125)
at com.ibm.servlet.engine.oselistener.OSEListenerDispatcher.service(OSEListener.java:315)
at com.ibm.servlet.engine.http11.HttpConnection.handleRequest(HttpConnection.java:60)
at com.ibm.ws.http.HttpConnection.readAndHandleRequest(HttpConnection.java:313)
at com.ibm.ws.http.HttpConnection.run(HttpConnection.java:242)
at com.ibm.ws.util.CachedThread.run(ThreadPool.java:122)

could anyone kind enough to help me?
i am a beginner in websphere, i have follow the WAS online document guide but still no help.hope you guys can give me some idea in what i have to do!

Go to logs of in WebSphere/AppSever directory. Open default_server_stdout.log. You may get the System.out printed out. Then, you may get a more specific error.
Jun Hong

thanks hong!
i find out that the problem is fail to load the JDBC driver for websphere, where should i place the ifxjdbc.jar file(the JDBC driver for informix)? i already add the ifxjdbc.jar file to the classpath of my machine.