Getting VDO null on postback on submit button in MVC controller

Hi,

I have a structure with a parent VDO with a collection of child VDO and the child VDO consists of collection of other VDO.
the structure is as below 
Public Class AVDO
{

        public string name {get ;set;}              
        public IList<BVDO>  bcollection { get ; set ;}
}

Public Class BVDO
{
  public xyz {get ; set;};
  public IList<CVDO> {get ; set;};
       
}

I am binding AVDO to my view and I could get the values displayed on my view. But when I do a submit : postback.. I get the object bcollection as null.
Please note: I have done the binding of the objects in the respective VOD's.

Able to get the values for name in AVDO but not for bcollection.

Can anyone let me know what have gone wrong here or is there any solution for it.

Thanks,
Sudhir