Align elements with weightsum

I am trying to align 3 elements; one ImageViewand two TextView, using for it WeightSum.

I assign WeightSum = 20and give the elements 1, 17 and 2 respectively. But instead of leaving me the full line, it seems to be putting me Weight = 1in each of the elements. This being the result.

The orange/black elements should occupy the entire width of the lines, and stay halfway.

Code

for(int i=0;i<data.Count; i++)
{
    //Líneas principales
    LinearLayout.LayoutParams lp;
    lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MatchParent, 125);
    oLinea = new LinearLayout(this);
    //oLinea.Orientation = Orientation.Horizontal;
    oLinea.LayoutParameters = lp;
    oLinea.WeightSum =20;

    //Reinstancio los parametros, 0 para que tenga en cuenta el peso y 125 para la altura
    lp = new LinearLayout.LayoutParams(0, 125);

    //ImageView
    ImageView iEstado = new ImageView(this);;
    lp.Weight = 1;
    iEstado.LayoutParameters = lp; 
    iEstado.SetScaleType(ImageView.ScaleType.FitCenter);

    //TextView1
    TextView tDescripcionGrupo = new TextView(this);
    tDescripcionGrupo.Text = data[i].toString();//Esto es irrelevante
    lp.Weight = 17;
    tDescripcionGrupo.LayoutParameters = lp;

    //TextView2
    TextView tEstado = new TextView(this);
    tEstado.Text = ""; //El String también es irrelevante.
    lp.Weight = 2;
    tEstado.LayoutParameters = lp; 

    //se añaden las listas a la línea
    oLinea.AddView(iEstado);
    oLinea.AddView(tDescripcionGrupo);
    oLinea.AddView(tEstado);

    //Se añaden las líneas a la layout activa.
    activeLayout.AddView(oLinea);      
}

I imagine that I have something wrong with the weights, or with some line parameter, but I've been trying for a long time and I still don't fully understand what needs to be done to make it Weightwork correctly.