how to change Object Stroke Color and fill Color?

Hi to all

i need to change fillcolor & stroke color of Object

here i wrote code that tried but it is not

myDoc = app.activeDocument;

var dd = myDoc.colors.add({name:"PANTONE Black C", model:ColorModel.spot, colorValue:[0, 13, 49, 98]});

app.findObjectPreferences= NothingEnum.NOTHING;
  app.changeObjectPreferences = NothingEnum.NOTHING;
  app.findObjectPreferences.fillColor = "Black";
  var myI1 = myDoc.findObject();   
   app.changeObjectPreferences.fillColor = "PANTONE Black C // here error throwing

    app.changeObject ();

app.findObjectPreferences= NothingEnum.NOTHING;
  app.changeObjectPreferences = NothingEnum.NOTHING;
  app.findObjectPreferences.strokeColor = "Black";
  var myI2 = myDoc.findObject();   
   app.changeObjectPreferences.strokeColor = "PANTONE Black C // here error throwing

    app.changeObject ();

Error is :  Invalid value for set property 'fillcolor' ,Expected Swatch, String or NothingEnum enumerator, but received "PANTONE Black C";

pls help me...

Thanks

Thangaraj