retrieve original adapter from expandablelistview with header

I'm using a ExpandableListView with a custom adapter that extends BaseExpandableListAdapter. Now I want to add a header to that expandable list, so instead of using my apapter to get the view of the elements I need to use the one "automatically" created with the header so I don't get a IndexOutOfBoundsExceptions because now the header is a element at 0 position.

In other ocassions where my adapter was not expandable I just need to call myList.getAdapter() and everything was ok but now I need to get the adapter that extends BaseExpandableListAdapter and I can't find the way to do it.

myList = (ExpandableListView)findViewById(R.id.my_list);
myList .setGroupIndicator(null);
myList .setOnGroupClickListener(this);
myList .setOnChildClickListener(this);

//add a header
View addSummaryLayout = View.inflate(this, R.layout.add_summary, null); 
groupedMultimediaListView.addHeaderView(addSummaryLayout);  

myAdapter = new MyAdapter (this, uploadingMedias);
myList .setAdapter(myAdapter );

At some time, I need to call the getChildView method for myAdapter (extends BaseExpandableListAdapter) but I can't use directly myAdapter because that one doesn't have the header. I need to do it through the list. I'm trying to do it through the getWrappedAdapter

HeaderViewListAdapter headerAdapter = ((HeaderViewListAdapter) myList .getAdapter());
((MyAdapter ) headerAdapter.getWrappedAdapter()).getChildView(0, i - 1, false, view, myList );

but it's giving me a ClassCastException, android.widget.ExpandableListConnector cannot be cast to MyAdapter

Does anyone know a way to get the original adapter through the list methods?

Thank you