new RenderTargetCube() throws sharpdx exception

I have a directx project and when I run this line:

new RenderTargetCube(graphics.GraphicsDevice, 256, true, new SurfaceFormat(), new DepthFormat())

I get this sharpdx exception:

HRESULT: [0x80070057], Module: [General], ApiCode: [E_INVALIDARG/Invalid Arguments], Message: The parameter is incorrect.

The stacktrace given in the exception is as follows:

** at SharpDX.Result.CheckError()
at SharpDX.Direct3D11.Device.CreateTexture2D(Texture2DDescription& descRef, DataBox[] initialDataRef, Texture2D texture2DOut)
at SharpDX.Direct3D11.Texture2D…ctor(Device device, Texture2DDescription description)
at Microsoft.Xna.Framework.Graphics.RenderTargetCube…ctor(GraphicsDevice graphicsDevice, Int32 size, Boolean mipMap, SurfaceFormat preferredFormat, DepthFormat preferredDepthFormat, Int32 preferredMultiSampleCount, RenderTargetUsage usage)
at Microsoft.Xna.Framework.Graphics.RenderTargetCube…ctor(GraphicsDevice graphicsDevice, Int32 size, Boolean mipMap, SurfaceFormat preferredFormat, DepthFormat preferredDepthFormat)**

It seems there is a problem creating a 2D texture. Anyone know why this is happening?