Index: AuthenticationService.java
===================================================================
--- AuthenticationService.java	(revision 412203)
+++ AuthenticationService.java	(working copy)
@@ -449,6 +449,7 @@
         }
 
         // try each authenticators
+        String explanations = "";
         for ( Iterator i = authenticators.iterator(); i.hasNext(); )
         {
             Authenticator authenticator = ( Authenticator ) i.next();
@@ -469,6 +470,12 @@
                 {
                     log.info( "Authenticator " + authenticator.getClass() + " failed to authenticate " + bindDn );
                 }
+                if (e.getMessage() != null && e.getMessage().trim().length() > 0) {
+                    if (explanations.length()>0) {
+                        explanations += " - ";
+                    }
+                    explanations += e.getMessage();
+                }
             }
             catch ( Exception e )
             {
@@ -477,10 +484,16 @@
                 {
                     log.warn( "Unexpected exception from " + authenticator.getClass() + " for principal " + bindDn, e );
                 }
+                if (e.getMessage() != null && e.getMessage().trim().length() > 0) {
+                    if (explanations.length()>0) {
+                        explanations += " - ";
+                    }
+                    explanations += e.getMessage();
+                }
             }
         }
 
-        throw new LdapAuthenticationException();
+        throw new LdapAuthenticationException(explanations);
     }
 
     /**