WPF Button에 Command Binding Error code 40 이슈

<DataTemplate> 안에서 

Command를 Binding 하는 부분에서 계속 이런 이슈가 생겼는데 

The problem that I have is getting my button to work with the binding. I'm not sure what to set the DataContext. I am getting this error with my binding:

System.Windows.Data Error: 40 : BindingExpression path error: 'ClickMeCommand' property not found on 'object' ''Person' (HashCode=13029119)'. BindingExpression:Path=ClickMeCommand; DataItem='Person' (HashCode=13029119); target element is 'Button' (Name=''); target property is 'Command' (type 'ICommand')

왜 안되는지 거의 하루? 반나절을 끙끙거리다가 

스택오버플로우 형님께서 DataTemplate안에서 Command 를 Binding 할 때 접근이 안된다고 

RelativeSource를 써서 해야한다고 알려주셨다......... 

 

앞으로 사용할 때 주의하자 !!

<DataTemplate>
                                    <Border Background="{Binding Path=Color}" BorderThickness="1" BorderBrush="Black" Margin="10,2,0,2" ToolTip="{Binding Path=SeriesID}">
                                        <StackPanel Orientation="Horizontal">
                                            <Button x:Name="btn_deleteItem" Command="{Binding RelativeSource={RelativeSource AncestorType=UserControl, Mode=FindAncestor}, Path=DataContext.btnClickCommand }" Padding="2" 
                                                     >
                                                <ContentControl >
                                                    <Image Source="minus-condition.png" />
                                                </ContentControl>
                                            </Button>
                                            <CheckBox IsChecked="{Bindin