I got stuck to draw a triangle using an index and DrawIndexed(), the triangle is not drawn. The windows just renders the blue background. While looking at other tutorials I think I did everything necessary to use an index, but maybe I am missing something?!

Edit: Solved (thx Unbird), the array data type did not match the format in SetIndexBuffer, changing it back to int to match the format did the trick. I updated the code below for the next one using indices for SharpDX
1) Index array and buffer at the class variables
 

        // Vertices
        private VertexPositionColor[] vertices = new VertexPositionColor[]

       {
            new VertexPositionColor(new Vector3(-0.5f, 0.5f, 0.0f), SharpDX.Color.Red),
            new VertexPositionColor(new Vector3(0.5f, 0.5f, 0.0f), SharpDX.Color.Green),
            new VertexPositionColor(new Vector3(-0.5f, -0.5f, 0.0f), SharpDX.Color.Blue),

        };

        // Indices
        private uint[] indices = new uint[] { 0, 1, 2 };
        // Vertice-Buffer / Index-Buffer
        private D3D11.Buffer vertexBuffer;
        private D3D11.Buffer indexBuffer;

2) Set the indexbuffer

        private void InitializeTriangle()
        {
            vertexBuffer = D3D11.Buffer.Create(d3dDevice, D3D11.BindFlags.VertexBuffer, vertices);
            indexBuffer = D3D11.Buffer.Create(d3dDevice, D3D11.BindFlags.IndexBuffer, indices);
        }

3) Draw-Method:
 

        /// <summary>
        /// Draw the scene.
        /// </summary>

        private void Draw()
        {
            //Re-Initialize triangle
            InitializeTriangle();

            // Set back buffer as current render target view
            d3dDeviceContext.OutputMerger.SetRenderTargets(renderTargetView);
            // Clear the screen
            d3dDeviceContext.ClearRenderTargetView(renderTargetView, new SharpDX.Color(32, 103, 178));

            // Draw the triangle on the screen
            d3dDeviceContext.InputAssembler.PrimitiveTopology = PrimitiveTopology.TriangleList;
            d3dDeviceContext.InputAssembler.SetVertexBuffers(0, new D3D11.VertexBufferBinding(vertexBuffer, Utilities.SizeOf<VertexPositionColor>(), 0));
            d3dDeviceContext.InputAssembler.SetIndexBuffer(indexBuffer, Format.R32_UInt, 0);

              d3dDeviceContext.DrawIndexed(3, 0, 0);

            // Swap front and back buffer
            swapChain.Present(1, PresentFlags.None);
      }

.

SharpDX_Tutorial_5_(using_an_index).zip

uint -> Format.R32_UInt

ushort -> Format.R16_UInt

Edit : Note that even after the edit you still use signed integers. Won't matter here though 

That was the error, thank you!!

Edit: damn you're right. Edited once again :-)