Signing xpi files

[Jeff Pudwell]

I have an xpi file that contains a plugin and support files that
needs to be installed for Netscape 6. I signed this xpi in the same
way I did for Netscape 4.x using the signtool but when the xpi
is installed Netscape 6 does not display our certificate, instead
it presents a dialog warning about installation of malicious software.

Has anyone managed to sign their xpi file and do I have to do
something differently?

Thanks,
Jeff