title: join and group by query works in firebird 2.1 but not in 1.5
body: <p>I have the following query that works fine in firebird 2.1, however I cannot get it to work on a db with the exact same structure in 1.5</p>
  
  <pre><code>select c.printchecknumber, v.voidamount 
  from checks c 
  join (select checknumber, sum(voidamount) as voidamount 
        from checkitem 
        where voidtype =1 
        group by checknumber) v on c.checknumber = v.checknumber 
  order by c.printchecknumber
  </code></pre>
  
  <p>Any ideas?</p>
  
  <p>The error message is
  Invalid token
  Dynamic SQL Error
  SQL error code = -104
  Token unknown - line 1, char 61
  the error is at the start of the second select</p>