//Step 1
this.ultraTimeSpanEditor1.Nullable = true;

//Step 2
this.ultraTimeSpanEditor1.Value = new TimeSpan(1, 8, 30, 12);
Console.WriteLine("Value is: " + this.ultraTimeSpanEditor1.Value);

//Step 3
this.ultraTimeSpanEditor1.Value = null;
Console.WriteLine("Value is: " + this.ultraTimeSpanEditor1.Value);

//Error
Value is always: 1.08:30:12

Best regards, Lello