classpath已设置完毕，但还是出现以下问题，请各位老大帮帮忙，多谢

java.sql.SQLException: [Microsoft][SQLServer JDBC Driver]ResultSet can not re-read row data for column 1.

import java.sql.*;
class Conn{
public Connection conn = null;
public Conn(){
String sDBDriver="com.microsoft.jdbc.sqlserver.SQLServerDriver";

try{
Class.forName(sDBDriver);
}catch(java.lang.ClassNotFoundException e){
System.err.println("opendb():"+e.getMessage());
}
try{
conn=DriverManager.getConnection("jdbc:microsoft:sqlserver://server:1433","OA","meijin");
conn.setCatalog("OA");

}
catch (SQLException ex){
System.err.println("rs.executeQuery:"+ex.getMessage());
}
}
public static void main( String argv[] )
{
Conn Conn = new Conn();

try{

Conn conn = new Conn();
Statement stmt = conn.conn.createStatement();

String sql="select * from OA_Employee where Employee_ID=4";
ResultSet rs=stmt.executeQuery(sql);
if(!rs.next()){
stmt.close();
}
String strEmpName = rs.getString("Employee_Name");
String strEmpID = rs.getString("Employee_ID");
System.out.println( "succeed" );
rs.close();

}catch(SQLException ex){
System.out.println(ex+"" );
}

System.out.println( "succeed@!!@!" );

}
}

if(rs.next()){
String strEmpName = rs.getString ("Employee_Name");
String strEmpID = rs.getString ("Employee_ID");
System.out.println( "succeed" );
}
rs.close();
         stmt.close();