cannot create bean shibboleth.DataSealer because of KeyNotFoundException

[Rainer Hoerbe]

To create a new data sealer keystore I use following values from idp.properties:
  #idp.sealer.aliasBase = secret
  idp.sealer.storePassword = password
  idp.sealer.keyPassword = password


Then I create the keystore as:
  rm -f sealer.jks
  keytool -genseckey -keystore sealer.jks -storetype JCEKS -alias secret \
       -keyalg AES -keysize 128 \
       -storepass password -keypass password


When starting the IDP jetty complains about not finding the key:

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'shibboleth.DataSealerKeyStrategy' defined in file [/opt/shibboleth-idp/system/conf/global-system.xml]: Invocation of init method failed; nested exception is net.shibboleth.utilities.java.support.component.ComponentInitializationException: Exception loading the default key
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1578)
	... 
Caused by: net.shibboleth.utilities.java.support.component.ComponentInitializationException: Exception loading the default key
	at net.shibboleth.utilities.java.support.security.BasicKeystoreKeyStrategy.doInitialize(BasicKeystoreKeyStrategy.java:226)
	... 94 common frames omitted
Caused by: net.shibboleth.utilities.java.support.security.KeyNotFoundException: Key was not present in keystore
	at net.shibboleth.utilities.java.support.security.BasicKeystoreKeyStrategy.getKey(BasicKeystoreKeyStrategy.java:290)
	… 

What am I missing? 

- Rainer