Unable to start several servers using the custom. authentication and authorization Provider

[My Chi Doan]

I downloaded the Sample Security Providers (http://developer.bea.com/managed_content/direct/SampleSecurityProvidersUnmanaged.zip)
and followed the user guide for installation.
We have following configuration:
- One domain with 3 servers :
- ADM: admin, console
- WTL_1 : WebTool server 1
- WTL_2 : WebTool server 2
WTL_1 and WT_2 are member of cluster WTL_Cluster

I try to restart all servers. It worked fine for the first one (ADM), but for
the other two I got followinf exception:

####<Nov 13, 2002 10:29:02 AM CET> <Emergency> <WebLogicServer> <isoit652.bbn.hp.com>
<WTL_1> <main> <kernel i
dentity> <> <000342> <Unable to initialize the server: Fatal initialization exception
Throwable: java.lang.SecurityException: Authentication denied: Boot identity not
valid
java.lang.SecurityException: Authentication denied: Boot identity not valid
at weblogic.security.service.SecurityServiceManager.doBootAuthorization(SecurityServiceManager.java:1024)
at weblogic.security.service.SecurityServiceManager.initialize(SecurityServiceManager.java:1166)
at weblogic.t3.srvr.T3Srvr.initialize1(T3Srvr.java:697)
at weblogic.t3.srvr.T3Srvr.initialize(T3Srvr.java:589)
at weblogic.t3.srvr.T3Srvr.run(T3Srvr.java:277)
at weblogic.Server.main(Server.java:32)

Do you have any idea why it worked only for one server?

Thanks for any help
My Chi