How to update the datasource of a Chart

hello.

i have chart on a usercontrol. (call chartcontrol) i have user control on header. ( call header control) have header on usercontrol. (mainuc)

when on mainuc want data on chartcontrol updated.

here i'm trying do...

on chartcontrol have exposed property

observablecollection

<datastuff> dataroot = new observablecollection<datastuff> { new datastuff{ date = datetime

.now, totalvalue=10} };

public observablecollection<datastuff

> bindingdata {

get { return

dataroot; }

set { dataroot = value

; }

}

public smalllinegraph() {
         initializecomponent();
         //buildsampleset();
         datetimeaxis oxaxes = (datetimeaxis)totalchart.axes[0];
         oxaxes.minimum = dataroot.orderby(c => c.date).take(1).singleordefault().date;
         oxaxes.maximum = dataroot.orderbydescending(c => c.date).take(1).singleordefault().date;

         linearaxis oyaxes = (linearaxis)totalchart.axes[1];
         oyaxes.minimum = (double?)dataroot.orderby(c => c.totalvalue).take(1).singleordefault().totalvalue;
         oyaxes.maximum = (double?)dataroot.orderbydescending(c => c.totalvalue).take(1).singleordefault().totalvalue;
         totalchart.datacontext = dataroot;
      }

public class datastuff : inotifypropertychanged {

private datetime mdate;
private decimal mtotalvalue;

      public datetime date {
         { return mdate; }
         set {
            mdate = value;
            this.notifypropertychanged("date");
         }
      }

      public decimal totalvalue {
         { return mtotalvalue; }
         set {
            mtotalvalue = value;
            this.notifypropertychanged("totalvalue");
         }
      }

public event propertychangedeventhandler propertychanged;

      public void notifypropertychanged(string propertyname) {
         if (this.propertychanged != null) {
            this.propertychanged(this, new propertychangedeventargs(propertyname));
         }
      }
   }

then on mainuc reference headeruc (salesheadingtotals) , try change data so.

salesheadingtotals.smallgraphtoday.bindingdata = buildsampleset();

observablecollection

<datastuff

> buildsampleset() {

observablecollection<datastuff> dataroot = new observablecollection<datastuff

>();

dataroot.add(