problem about premission grant on signned jar file

[mic]

i have signned a jar file and put the public key in the correct place,
however, the runtime env complain about this:

java.security.cert.CertificateException: Unable to verify the certificate
with root CA
at sun.plugin.security.TrustDecider.isAllPermissionGranted(Unknown Source)
at sun.plugin.security.PluginClassLoader.getPermissions(Unknown Source)
at java.security.SecureClassLoader.getProtectionDomain(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at sun.applet.AppletClassLoader.findClass(Unknown Source)
at sun.plugin.security.PluginClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadCode(Unknown Source)
at sun.applet.AppletPanel.createApplet(Unknown Source)
at sun.plugin.AppletViewer.createApplet(Unknown Source)
at sun.applet.AppletPanel.runLoader(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

i do know why it says" java.security.cert.CertificateException: Unable to
verify the certificate with root CA"
i can solve showWindowWithoutWarningBar and reading file permission , so i
sure the keystore is in correct place
i am using jdk1.3.1
thanks,
mic