Cannot convert from SQL type 0 to C type 4.

My Code below displays an error as such:

Error:- Exception: [JDBC Progress Driver]:Unable to convert column 1. Cannot convert from SQL type 0 to C type 4.

Can anyone explain me the reason? How to overcome this error?

I had this program working on 9.1E, but running the same on 10.1C displays an error?

Is there any change in the SQL syntax or change in the results format for progress10.1C driver?

try{
           Connection con=null;
           Statement stmt;
           Class.forName("com.progress.sql.jdbc.JdbcProgressDriver");
           con=DriverManager.getConnection("jdbc:JdbcProgress:T:10.180.161.140:15500:prodproxy","test","test");
           stmt=con.createStatement();
                                 
            ResultSet rs = stmt.executeQuery("SELECT count(*) FROM pub.ctry_mstr");
            while (rs.next()) {
            int numberOfRows = rs.getInt(1);  *// ERROR in THIS LINE*
           System.out.println("Number of Rows : " +numberOfRows);
}
    } catch(Exception ex) {
                                       System.out.print("Exception: ");
                                       System.out.println(ex.getMessage());
                                  }