I have a problem in Imoport Definition portlet of alert. I add this portlet in a page. It displays an error message like:

An error has occurred while processing your request: com/bowstreet/solutions/alerting/impl/database/GenericAlertDefProxy

Show Error Detail Hide Error Detail

java.lang.NoClassDefFoundError: com/bowstreet/solutions/alerting/impl/database/GenericAlertDefProxy
at com.bowstreet.solutions.alerting.impl.database.Dat abasePersistenceManager.getAlertDefs(DatabasePersi stenceManager.java:197)........

Does anyone has idea what is going on there? Thansk!