Jxl workbook erro

Estou tendo problemas com o jxl.Workbook ele retorna o erro:

Prototipo01.java:11: error: cannot find symbol
Workbook workbook = Workbook.getWorkbook(new File("myfile.xls"));
^
  symbol:   class Workbook
  location: class principal
Prototipo01.java:11: error: cannot find symbol
Workbook workbook = Workbook.getWorkbook(new File("myfile.xls"));
                    ^
  symbol:   variable Workbook
  location: class principal
2 errors

quando vou transformar o arquivo .java em .class o código e esse:

package jxl;
import java.io.File;
import java.util.Date;
import jxl.*;

class principal {

public static void main(String[] args){


Workbook workbook = Workbook.getWorkbook(new File("myfile.xls"));


}
}