How to implement a standard cubemapped skybox?

Thanks for the help ! My problem is that I was importing the texture as a .png which comes in as a Texture2D, while TextureSampleParameterCube wants a TextureCube. I was able to export as a .hdr file through Blender and it imported and displays (somewhat) correctly.

I’m having a different problem now. I can’t figure out why the texture seems to import with a max in-game size of 512x512. The source is 2048x1024 which Unreal Engine seems to identify.
Screenshot: http://i.imgur.com/vTBAJrW.png

The HDR image in question: equi.hdr

I don’t understand why I’m being limited to 512x512. It definitely makes the image and resulting skybox fuzzy. I’ll do some source diving tomorrow to see if it is some oddity in the Radiance HDR import code. Have you run into anything like this before?

To clarify, my goal here is to have a high resolution skybox (current image is 2048x1024). I’m doing so by exporting an equirectangular Radiance HDR image from Blender. The texture seems to import fine but is capped at 512x512. It’s worth noting that the engine assets at \Engine\MapTemplates\Sky including SunsetAmbientCubemap, Desert_Outer_HDR, and DaylightAmbientCubemap all exhibit this behavior of having greater than 512x512 dimensions but being capped.