Problem rendering particles in ios

Hi,

I have a problem rendering a particle system in ios. While it runs fine in the editor, it doesn't look the same while I run the game on an ipad mini. I tried different shaders but nothing seems to work. Here follows the code and I have also attached two screenshots to show the problem.

Many thanks for the help, I hope my question is not too newbie.

Thanks Ioannis

      void Awake () {
         GameObject parent = new GameObject ("test");
         ParticleSystem particlesystem = parent.AddComponent<ParticleSystem> ();
         ParticleSystem.Particle[] p = new ParticleSystem.Particle[1];
         p [0].size = 2;
         p [0].position = new Vector3 (0, 10, 0);
         p [0].color = Color.green;

         ParticleSystemRenderer pr = (ParticleSystemRenderer)particlesystem.renderer;
         pr.renderMode = ParticleSystemRenderMode.Billboard;
         pr.sortingOrder = 1;
         
         particlesystem.renderer.material.shader = Shader.Find ("Mobile/Particles/Additive");
         //particlesystem.renderer.material.shader = Shader.Find ("Mobile/Particles/Additive Culled");
         //particlesystem.renderer.material.shader = Shader.Find ("Mobile/Particles/Alpha Blended");
         //particlesystem.renderer.material.shader = Shader.Find ("Mobile/Particles/Multiply");
         //particlesystem.renderer.material.shader = Shader.Find ("Mobile/Particles/Multiply Culled");
         //particlesystem.renderer.material.shader = Shader.Find ("Mobile/Particles/VertexLit Blended");
         //particlesystem.renderer.material.shader = Shader.Find ("Mobile/Transparent/Vertex Color");
         //particlesystem.renderer.material.shader = Shader.Find ("Sprites/Default");

         particlesystem.SetParticles (p, 1);
         particlesystem.startSpeed = 0;
         particlesystem.startSize = 0;
         particlesystem.Emit (1);
         particlesystem.Pause ();
     }