problems in signed applet

[Ori Helman]

Hello,
i have created a java applet. it runs good on ie4 and above.
when i tried to run it on netscape 4.7 it gives me this error:
"Applet wow.SyncApplet class wow .SyncApplet could not be loaded"

the applet is in a jar and it is signed.
i also implemented all the Capabilites API.

when i try to run my applet not in a jar, it work just fine.

what can be the problem?

TIA
ori