Put your behaviour where it belongs

badway.cs

// This could just as easily be a command handler in a view model
private void AcceptButton_Clicked(object sender, EventArgs e)
{
   if (CurrentNetWeight <= 0)
      throw new Exception("Can not accept weights that <= 0");

   Load.GrossWeight = GrossWeight;
   Load.TareWeight = TareWeight;
   Load.NetWeight = CurrentNetWeight;
   Load.WeightAcceptedTime = DateTime.Now;
}

goodway.cs

// This could just as easily be a command handler in a view model
privte void AcceptButton_Clicked(object sender, EventArgs e)
{
   // Much better the behaviour and checks related to accepting a weight
   // Can go where they belong now
   Load.AcceptWeights(GrossWeight, TareWeight);
}