Hi All,

I am trying to create some line charts from a dataset and getting an error (WPF+WPF Toolkit + C#):

Nullable object must have a value

Here is a code that I use to add some data points to the chart:

 ObservableCollection points = new ObservableCollection();

foreach (DataRow dr in dc.Tables[0].Rows)
                {
                     points.Add(new VelChartPoint()
                    {
                        Label = dr[0].ToString(),
                        Value = double.Parse(dr[1].ToString())
                    });

                }

Here is a class VelChartPoint

public class VelChartPoint : VelObject, INotifyPropertyChanged {

        public DateTime Date
        {
            get;
            set;
        }

        public string Label
        {
            get;
            set;
        }

        private double _Value;
        public double Value
        {
            get {
                return _Value;
            }
            set {

                    _Value = value;

                var handler = PropertyChanged;
                if (null != handler)
                {
                    handler.Invoke(this, new PropertyChangedEventArgs("Value"));
                }
            }
        }

        public string FieldName
        {
            get;
            set;
        }

        public event PropertyChangedEventHandler PropertyChanged;

        public VelChartPoint() { }

    }

So the problem occures in this part of the code

points.Add(new VelChartPoint
                {
                    Name = dc.Tables[0].Rows[0][0].ToString(),
                    Value = double.Parse(dc.Tables[0].Rows[0][1].ToString())
                }
    );

I've made some tests, here are some results i've found out. This part of code does'nt work for me:

string[] labels = new string[] { "label1", "label2", "label3" };

            foreach (string label in labels)
            {
                points.Add(new VelChartPoint
                {
                    Name = label,
                    Value = 500.0
                }
                );

            }

But this one works fine:

 points.Add(new VelChartPoint
                {
                    Name = "LabelText",
                    Value = double.Parse(dc.Tables[0].Rows[0][1].ToString())
                }
    );

Please, help me to solve this error.