Problem signing executable jar's

[Dave Robbins]

Hello All,
I want to deploy an app as a webstart application that will need to be signed
I've floowed these directions to create an executable jar file
http://csdl.ics.hawaii.edu/~johnson/613f99/modules/04/jar-files.html
at this point it runs properly from the command line
java -jar myapp.jar
but when I sign it, it stops runing, I get this error
Failed to load Main-Class manifest attribute from myapp.jar
I used these direction for creating the key
http://www.dallaway.com/acad/webstart/
and everything seems to work correctly except that tricky part at the end where my app wont run

here are my commands to create and sign the jar
jar cmf mainClass myapp.jar myapp
now it runs with this "java -jar myapp.jar"
jarsigner -keystore keystore myapp.jar me

now "java -jar myapp.jar" fails
Any Ideas???
Thanx
Dave