c# design time serialization

I'm trying to add a string to the Property Grid at design time but can't figure out why it isn't working.
 
[DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
[Category("Design Time")]
[Description("Question to be Asked")]
[Browsable(true)]
public string Question { get; set };
 

I want to be able to see "Question" on the property grid, so that I can write text and have it serialized at design time.
 
What am I doing wrong?