using postgresql-8.0-311.jdbc2.jar

Dear sir,

          I was interfacing with postgreSQL 7.1.3 from my application
using the JDBC driver released with it. Now,I'm trying to communicate
with postgreSQL 8.0.3 with postgresql-8.0-311.jdbc2.jar. PostgreSQL
8.0.3 server is running on another machine in LAN. My application
connects to the server using postgresql-8.0-311.jdbc2.jar. While it is
possible to connect to the server,the response for each query is empty
data though there's data in server for the given query. The following
method is used to execute each query:

public Vector TableQuery(String instruction)  {

    SQL = instruction;
    Vector queryResult= new Vector(); //Vector de vectores
    Vector TableRow = new Vector();
    TableHeader = new Vector();
    ResultSet rs;

    try {
          rs = st.executeQuery(instruction);
          ResultSetMetaData rsmd = rs.getMetaData();
          // Extraer Nombres de Columnas
          int cols = rsmd.getColumnCount();
          for(int i=1;i<=cols;i++)
            TableHeader.addElement(rsmd.getColumnLabel(i));
          // Extraer registros
          int num = rs.getFetchSize();

          if (num>0) {

              while (rs.next()) {

                     TableRow = new Vector();

                     for  (int i=1;i<=cols;i++) {

                          Object o = rs.getObject(i);

                          if (rs.wasNull())TableRow.addElement(o);
                      }

                     queryResult.addElement(TableRow);
                }
               wasFail = false;
            }
      }
    catch(Exception ex) {
          wasFail = true;
          problem = ex.getMessage();
          System.out.println("Error: " + ex);
          ex.printStackTrace();
       }

    return queryResult;
  }

No exception is thrown. It should be noted that the same snippet works
if I use the JDBC driver given with postgreSQL 7.1.3 to communicate with
postgreSQL 8.0.3.

What could the problem be?
Thanks in advance.

sincerely,
Sarveswaran M