add random walls with an array in 3D xna 4

I'm trying to add walls to my 3D game. I created a wall entity and added model array

public Walls()
{
  modelArray = new Model[10];
}

public void Initialize(ContentManager contentManager)
{
  for (int i = 0; i < modelArray.Length; i++)
  {
    rnd = new Random();
    sidesWall = rnd.Next(-4, 4);
    forwardWall = rnd.Next(-8, 0);
    modelArray[i] = contentManager.Load<Model>("wall");
  }
}

Draw method:

public void Draw(Camera camera)
{
  foreach (Model m in modelArray)
  {
    foreach (ModelMesh mesh in m.Meshes)
    {
      foreach (BasicEffect effect in mesh.Effects)
      {
        effect.EnableDefaultLighting();
        effect.PreferPerPixelLighting = true;
        effect.World = GetWorldMatrix();
        effect.View = camera.ViewMatrix;
        effect.Projection = camera.ProjectionMatrix;
      }

      mesh.Draw();
    }
  }
}

It doesn't work and it shows only one wall.

How can I make it work?