jar file error

I have 2 class called Box and BoxTest , I create a jar file using the command

jar cfe ch.jar app.txt Box.class Boxtest.java Boxtest.class

Then it create a jar file call ch

app.txt file contain my main class.Here what it contain

Main-Class: BoxTest

But when I run it using java -jar ch.jar compiler throws an error msg.

Exception in thread "main" java.lang.NoClassDefFoundError:app/txt

Can some one help me.Thanks..

[468 byte] By [jolaa] at [2007-11-27 11:11:49]