Asp.net Get Object via Web-Service Calls From Javascript

Hi,
I am trying to make some WS method calls from Javascript and get some complex data but it is a little weird..
I have a class called <Classified> and inside this I have another class called <ClassifiedMediaCollection> which represents the media(photos,video) of a specified <Classified> object...
My javascript method calls a C# function which returns <ClassifiedCollection> data which is  List of <Classified> objects.
Javascript succededCallback function can read the result i.e result[i].Name but it cannot read the result[i].ClassifiedMediaCollection[y].Source member which is <undefined>...It recognizes that result[i].ClassifiedMediaCollection length is > 0 but it cannot access the members of the embedded object <ClassifiedMediaCollection> of the object <Classified>
What might be wrong with this?
Thanks in advance,
Kostas.
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