MessageBox Quick Help

[CaliberC]

I Followed the Instruction on the MSDN to create a Yes/No Msg Box Popup that Recieves an INPUT. and Ended up with Below

But When i Compile i get...
""""error C2065: 'Yes' : undeclared identifier""""

if(MessageBox::Show("SSS?","My",MessageBoxButtons::YesNo,MessageBoxIcon::Question) == DialogResult::Yes)
      {
		//What to DO if it is YES Goes HERE
	}

Its Literally Copy/Pasted from MSDN so what happened?