DropDownDataGrid not binding changed value when inside DataGrid

I'm trying to save the DropDownDatagrid changed value. The grid.Value is always empty but when i change the "Data" field it works. See the screens below.

When I change the "Data" field it saves the record but when i only change "Conta Crédito" or "Conta Débito" the grid0.Value comes with no values. See the code below:

I've found a solution. Instead of use grid0.Value, replaced it with grid0.Data.ToList(). This way i get the data selected from the DropDownDatagrid.