Changing the color of an object

I have tried very unsuccessfully to change the color of an object:

My simplest approach has been:

//  The current color of a pgf format is Black and I want to change it to Royal Blue

var myobject =  MyDoc.GetNamedObject(Constants.FO_PgfFmt,"Heading-3")

myobject.Color.Name = "Royal Blue";

alert(myobject.Color.Name)  // the colour is still Black

I have also tried:

var mycolorprops = myobject.Color.GetProps()

var i  = GetPropIndex(myobject.Color,Constant.Name)

mycolorprops[i].propVal.ival =  Constants.FV_COLOR_ROYALBLUE        

                                     or

mycolorprops[i].propVal.sval =  "Royal Blue"

If I can solve for Color then I will be able to work with all other commands that involve Properties.