今天写hql，遇到了个问题：could not locate named parameter [startDate]

sql如下：

Finder f = Finder.create("select bean from Statistics bean ");
  f.append(" where Date(bean.createTime) >= startDate and " +
    " Date(bean.createTime) <= endDate ");

开始以为是因为startDate未传值，然后对空值进行了处理！结果这个错误还在！然后仔细查看了sql，发现是因为startDate前少了：，正确sql如下：

Finder f = Finder.create("select bean from Statistics bean ");
  f.append(" where Date(bean.createTime) >= :startDate and " +
    " Date(bean.createTime) <= :endDate ");