I have a problem with a jar file

I create a jar file with JarWizard in windows but when i try to execute the jar in unix , don't work and throw this message "Failed to load Main-Class manifest attribute from /jars/CityDir" and i don't know why.

My MANIFEST.MF file is this:

Manifest-Version: 1.0

Main-Class: LeeDirectorio

Created-By: 1.3.1_08 (BEA Systems, Inc.)

where LeeDirectorio is the class with the main.

if anybody know why don't work my jars, please tell me.

Thanks.

[500 byte] By [Elessar.82] at [2007-9-30 12:24:45]