Query won't parse, why?

[alexg79]

I have the following named query:

@NamedQuery(name = SalesOrderExtraChargeLine.QUERY_UNBILLED_DATERANGE, query =
"SELECT el FROM SalesOrderExtraChargeLine el WHERE el.order.orderDate >= :startDate AND el.order.orderDate <= :endDate AND el.invoiceLines IS EMPTY AND NOT EXISTS (SELECT pl FROM SalesOrderProductLine pl WHERE pl.order = el.order AND pl.status <> :deliveredStatus)")

When I deploy the app, I get the following error:

17:57:06,287 WARN [ServiceController] Problem starting service persistence.units:ear=Etikettu.ear,jar=Etikettu-EJB.jar,unitName=etikettu
java.lang.NullPointerException
 at org.hibernate.hql.ast.tree.FromClause.findIntendedAliasedFromElementBasedOnCrazyJPARequirements(FromClause.java:120)
 at org.hibernate.hql.ast.tree.FromClause.getFromElement(FromClause.java:107)
 at org.hibernate.hql.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:81)
 at org.hibernate.hql.ast.tree.FromClause.addFromElement(FromClause.java:70)
 at org.hibernate.hql.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:255)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3056)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:2945)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:688)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:544)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.collectionFunctionOrSubselect(HqlSqlBaseWalker.java:4253)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.comparisonExpr(HqlSqlBaseWalker.java:3968)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1762)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1737)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.logicalExpr(HqlSqlBaseWalker.java:1690)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.whereClause(HqlSqlBaseWalker.java:776)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:577)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:281)
 at org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:229)
 at org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:228)
 at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:160)
 at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:111)
 at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:77)
...

SalesOrderProductLine and SalesOrderExtraChargeLine are both inherited from the same base entity (SalesOrderLine) using "JOINED" inheritance.
What am I doing wrong?