XNA problem

[Lordadmiral Drake]

Während dieser code:

protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // Copy parent transforms
            Matrix[] transforms = new Matrix[myModel.Bones.Count];
            myModel.CopyAbsoluteBoneTransformsTo(transforms);

            //Draw model, loop for multiple meshes
            foreach (ModelMesh mesh in myModel.Meshes)
            {
                //Set mesh orientation, cam and projection
                foreach (BasicEffect effect in mesh.Effects)
                {
                    effect.EnableDefaultLighting();
                    effect.World = transforms[mesh.ParentBone.Index] * Matrix.CreateFromQuaternion(pShipRotation) * Matrix.CreateTranslation(modelPos);
                    effect.View = viewMatrix;
                    effect.Projection = projectionMatrix;

                }
                mesh.Draw();
            }
            
        }

problemlos ausgeführt wird und mir mein Testraumschiffsmodell auf den Bildschirm zeichnet, erzeugt folgender code:

protected void DrawStarsphere()
        {
            foreach (ModelMesh mesh in starsphere.Meshes)
            {
                foreach (BasicEffect effect in mesh.Effects)
                {
                    effect.EnableDefaultLighting();
                    effect.World = Matrix.Identity * Matrix.CreateRotationY(starsphereRotation) * Matrix.CreateTranslation(modelPos);
                    effect.View = viewMatrix;
                    effect.Projection = projectionMatrix;
                }
                mesh.Draw();
            }
        }

folgenden Fehler:

Das Objekt des Typs "Microsoft.Xna.Framework.Graphics.Effect" kann nicht in Typ "Microsoft.Xna.Framework.Graphics.BasicEffect" umgewandelt werden.

Ich blick da nicht durch, was läuft falsch?