Having Problems with BeanUtils..

I am trying to use BeanUtils(Spring 3.0.5) to copy properties from one hierarchy to another. Following is what I use BeanUtils.copyProperties(source, dest);

My source is as follows

School is a class which has a collection of ClassPeriodType . ClassPeriodType is derived from PeriodType and adds its own properties to it as well.

PeriodType (has startDate,endDate,reason)
||
ClassPeriodType (it derives from the PmabPeriodType

public class School{
private List<ClassPeriodType> periods;
}

My dest is as follows
Company as a class which has a collection of PlanPeriods .
public class Company
{

private List <PlanPeriod> periods;
// getters and setters and other properties omitted for brevity
}
PlanPeriod has startDate,endDate as its properties.(no hierarchy here) .

//Code snippet
Company dest=new Company();
School school =new School();
school.addPeriods (// new set of ClassPeriodType periods added)
// What i am expecting here is to have the Company with a list of PlanPeriod types when i do this..
BeanUtils.copyProperties(source, dest);

instead what i am getting is Company -> List<ClassPeriodType> periods instead of Company-> List<PlanPeriod>.
The reflection is not happening throughout both the source and destination hierarchy . How do i achieve this ?

Cheers
Vaidya

Has anyone seen this problem? Or do the hierarchies need to match exactly ? Would using converters be the way to go for these kind of conversions?