diff --git a/src/java/org/apache/lenya/ac/attr/impl/AttributeManagerImpl.java b/src/java/org/apache/lenya/ac/attr/impl/AttributeManagerImpl.java
index a46f2a8..fb48896 100644
--- a/src/java/org/apache/lenya/ac/attr/impl/AttributeManagerImpl.java
+++ b/src/java/org/apache/lenya/ac/attr/impl/AttributeManagerImpl.java
@@ -52,7 +52,7 @@
             try {
                 attrs = (AttributeSet) this.attrSetSelector.select(name);
             } catch (ServiceException e) {
-                throw new RuntimeException();
+                throw new RuntimeException(e);
             }
             this.name2attributeSet.put(name, attrs);
         }
diff --git a/src/java/org/apache/lenya/ac/shibboleth/ShibbolethAuthenticator.java b/src/java/org/apache/lenya/ac/shibboleth/ShibbolethAuthenticator.java
index faae8ba..06712a4 100644
--- a/src/java/org/apache/lenya/ac/shibboleth/ShibbolethAuthenticator.java
+++ b/src/java/org/apache/lenya/ac/shibboleth/ShibbolethAuthenticator.java
@@ -494,6 +494,10 @@
 
     public AttributeSet getAttributeSet() {
         if (this.attributeSet == null) {
+            if (this.attributeSetHint == null) {
+                throw new RuntimeException("The parameter 'attribute-set' was not set. "
+                        + "Please check $WEBAPP_HOME/WEB-INF/cocoon.xconf.");
+            }
             try {
                 this.attributeManager = (AttributeManager) this.manager.lookup(AttributeManager.ROLE);
                 this.attributeSet = this.attributeManager.getAttributeSet(this.attributeSetHint);