title: glTexImage2D causes GL_INVALID_OPERATION
body: <p>This is my (wrapped) OpenGL call which causes a <code>GL_INVALID_OPERATION</code>:</p>
  
  <pre><code>GLTextures.TexImage2D(TexImage2DTarget.TEXTURE_2D, 0, TexImageInternalFormat.LUMINANCE_ALPHA, Width, Height, TexImageFormat.LUMINANCE_ALPHA, TexImagePixelType.UNSIGNED_BYTE, source.GetData());
  </code></pre>
  
  <p>This call works on Windows but not on iOS, in Windows everything works fine and the texture is displayed. I use the same enum-values on iOS and Windows and even the shader is the same ( with some precision hints on iOS ). Also the most textures are working on iOS.</p>