DataGrid binding in DataTemplate

I'm currently trying to do some binding inside of a datagrid but I'm having problems getting up to the level of DataContext of the view.

Here is the code:

<DataGridTemplateColumn.CellEditingTemplate><DataTemplate><ComboBox SelectedItem="{Binding Operators}"ItemsSource="{Binding DataContext.OperatorList,ElementName=FilterGrid}" /></DataTemplate></DataGridTemplateColumn.CellEditingTemplate>

Any ideas on whats wrong? The View's Viewmodel is connected in the code behind.

EDIT: The Binding that is not working is the ItemsSource binding shown above