Failed upgrade from 1.6.1 to 2.0

ERROR - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dbControlFactory' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: 
Could not instantiate bean class [com.cenqua.crucible.hibernate.DBControlFactoryImpl]: Constructor threw exception; nested exception is com.cenqua.crucible.hibernate.CruDBException: Problem upgrading with script /usr/local/crucible-2.0.0/sql/HSQL/upgrade/upgrade_30.sql: 
SQL script error on line 268: "alter table cru_comment add constraint FKE5A1D10644A616B5 foreign key (cru_review_id) references cru_review;" 
(Integrity constraint violation - no parent 19, table: CRU_COMMENT in statement [alter table cru_comment add constraint FKE5A1D10644A616B5 foreign key (cru_review_id) references cru_review]), please contact http://www.atlassian.com/support/
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:254)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:925)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:835)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:440)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)