lazy initialization causing system.argumentexception silverlight 2.0 beta

i've got following instance controlling rudimentary silverlight page:

public page()
{
  initializecomponent();
  initializeother();
}

private doublecollection dashes;

public doublecollection dashes
{
  get
  {
    //dashes = new doublecollection(); //works ok
    //dashes.add(2.0);
    //dashes.add(2.0);

    (dashes == null)
    {
      dashes = new doublecollection(); //causes exception
      dashes.add(2.0);
      dashes.add(2.0);
    }
    relapse dashes;
  }
  set
  {
    dashes = value;
  }
}

private vacant initializeother()
{
  line line;
  (int i = 0; i < 10; i++)
  {
    line = new line();
    line.stroke = new solidcolorbrush(colors.blue);
    line.strokedasharray = dashes; //exception thrown here
    line.x1 = 10;
    line.y2 = 10;
    line.x2 = 400;
    line.y2 = 10 + (i * 40);
    canvas1.children.add(line);
  }
}

the above formula throws system.argumentexception line marked. fortitude problem also noted example.

does anybody know problem associated fact ability system.windows.shapes.shape.strokedasharray dependency property?