Classes stored in Dictionary of base class - then calling functions in inherited classes

Question

I have a number of classes all inherited from the same base class (clsComponent). I store these in

        public Dictionary<string, clsComponent> Components = new Dictionary<string, clsComponent>();

I add objects of inherited classes to this dictionary. One example (several other classes but just an example)

                        Components.Add("COMP", new clsCompressor(this,Settings, new RectangleF(50,50,50,50)) );

So now I expect to cycle through the classes in Components, redefine their position and paint them

        public void PaintSystem(Graphics grph)
        {
            grph.Clear(Color.White);
            Region reg = grph.Clip;
            RectangleF rectot = reg.GetBounds(grph);

            foreach (KeyValuePair<string, clsComponent> entry in Components)
            {
                entry.Value.UpdateLocation(rectot);
                entry.Value.Paint(grph);
            }

UpdateLocation is a sub in the base class so that works fine. Paint is a sub in the base class, but hidden by another Paint in each inherited class. So when I do this UpdateLocation works fine, but Paint is calling the sub in the base class, not in the derived that was entered in the Dictionary.

Paint sub in base class :

     public void Paint(Graphics grph) { }

Paint sub in its inherited class:

public class clsCompressor : clsComponent
  {
      public clsCompressor(clsRefrigeration Syst, clsSettings Set, RectangleF PctLoc) 
      { 
          RefSystem = Syst;
          Settings = Set;
          PctLocation = PctLoc;
      }

      clsRefrigeration RefSystem = null;
      clsSettings Settings = null;


      new public void Paint(Graphics grph)
      {
    // do the real painting here          
      }

  }

When cycling in the above foreach the type of entry.Value is the correct class, not the base class, so why does it call the wrong function ?