Callnotfoundexception

hi Dear,


import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;


public void ReadXL(String Path) throws Exception
{
FileInputStream myStream=null;

System.out.println("InReadxl");
File xlFile = new File(Path);

myStream = new FileInputStream(xlFile);
HSSFWorkbook myWB = new HSSFWorkbook(myStream);

...........................

}

HSSFWorkbook myWB = new HSSFWorkbook(myStream); is creating
ClassNotFoundException() after adding external jar file
"poi-3.7-20101029".What might be causing the prolem?Please,let me know
the soultion of this problem.

Thanks