Merge to HDR Pro is resulting in a different image, and the 8 bit and 16 - bit sliders don't preview

In Cs6 whenever I touched any of the sliders the image in the preview panel changed quite nicely, now when I start the HDR Pro it comes up with a black image in the preview panel. Thats easy to fix though I switch from 16 bit or 8 bit to 32 bit the preview shows up and I can click on the 16 or 8 bit modes and it shows a preview. Then when I adjust any of the sliders nothing happens. I can play with the sliders as much as I want nothing happens. I have been using the 32 bit mode in cunjunction with the 'tone in ACR' setting which gives great results, but now I wanted to play with the scott5 preset. If I click ok it creates the image beautifully. So not only won't it preview but my image is completely different to what is in the preview panel.