neutral density - Why are my long-exposure photos (with ND filter) overexposed?

I am using a Nikon D90 and this is my first time trying to take long exposure photos.

I have set the camera to Manual mode, exposure compensation to -5, Bulb mode, f/22 aperture, ISO 100, 6-stop ND filter, on a tripod, and using a wireless remote. When I shoot with these settings in broad daylight I can see nothing but total blank white image.

I tried the same setup in other modes; I am able to see the image, but I don't see those lovely dreamy clouds like we normally do in long exposure.

Where am I going wrong?