Custom Vertical Seekbar height not being set correctly

I am trying to build an app which will need vertical sliders so I am buidling a custom SeekBar. I have managed to get a seekbar on screen which is correctly shown vertically but I can't find how to set the height dynamically so that it shows properly- at the moment it is sort of squished into one row of the Linear Layout.

I am very familiar with C# but Android is new to me so this may well be a basic error but I am getting so frustrated!

Here is my custom class:

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Util;
using Android.Runtime;
using Android.Views;
using Android.Widget;

namespace Lightslides001
{
public class BCSeekBar : SeekBar
{


    protected BCSeekBar(IntPtr javaReference, JniHandleOwnership transfer)
        : base(javaReference, transfer)
    {
    }

    public BCSeekBar(Context context)
        : base(context)
    {
    }

    public BCSeekBar(Context context, IAttributeSet attrs)
        : base(context, attrs)
    {
    }

    public BCSeekBar(Context context, IAttributeSet attrs, int defStyle)
        : base(context, attrs, defStyle)
    {
    }

    private int _min = 0;
    public int Min { get { return _min; } set { _min = value; } }

    public override int Progress
    {
        get
        {
            return base.Progress + _min;
        }
        set
        {
            base.Progress = value;
        }
    }

    public override int Max
    {
        get
        {
            return base.Max + _min;
        }
        set
        {
            base.Max = value + _min;
        }
    }

    public override void Draw(Android.Graphics.Canvas canvas)
    {
        canvas.Rotate(90);
        canvas.Translate(0, -this.Width);
        base.OnDraw(canvas);
    }

    public object GetInputData()
    {
        return (Progress + _min).ToString(CultureInfo.InvariantCulture);
    }

    protected void Measure(int widthMeasureSpec, int heightMeasureSpec)
    {
        base.Measure(heightMeasureSpec, widthMeasureSpec);
        SetMeasuredDimension(MeasuredHeight, MeasuredWidth);
    }

    public void OnSizeChanged(int w, int h, int oldw, int oldh)
    {
        base.OnSizeChanged(h, w, oldh, oldw);
    }

    public bool OnTouchEvent(MotionEvent evt)
    {
        if (!Enabled)
            return false;

        switch (evt.Action)
        {
            case MotionEventActions.Down:
            case MotionEventActions.Move:
            case MotionEventActions.Up:
                {
                    Progress = ((int)(Max * evt.YPrecision / Height));
                    OnSizeChanged(Width, Height, 0, 0);
                }
                break;
            case MotionEventActions.Cancel:
                break;
        }

        return true;
    }
}


}

And here is my activity:

 using System;
 using Android.App;
 using Android.Content;
 using Android.Runtime;
 using Android.Views;
 using Android.Widget;
 using Android.OS;
 using Android.Content.PM;

 namespace Lightslides001
 {
 [Activity(Label = "Lightslides001", 
    MainLauncher = true, 
    Icon = "@drawable/icon",
    ScreenOrientation=ScreenOrientation.Landscape)]

public class Activity1 : Activity
{
    int count = 1;

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main);

        // Get our button from the layout resource,
        // and attach an event to it
        Button button = FindViewById<Button>(Resource.Id.MyButton);

        button.Click += delegate { button.Text = string.Format("{0} clicks!", count++); };

        var seekbar = new BCSeekBar(this);
        seekbar.LayoutParameters = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WrapContent, LinearLayout.LayoutParams.FillParent);

        var ll = FindViewById<LinearLayout>(Resource.Id.layout1);

        ll.AddView(seekbar);

    }
}
 }

I really hope someone can help, thanks!