PS HDR Merge

I have been playing around a little with the HDR merge option in PS.
When you use bracketing in the camera then it works.
I was hoping that I could use it on RAW images as well. I have some nice results by playing with layers and layer masks in PS when combining two different exposures out of a single RAW image.
The Merge to HDR wizard from PS however allways claims that there is not enough dynamic range when making two or three different exposures from a single RAW image.
Has anyone succeeded in getting HDR merge to work from a raw image.
When playing with exposure settings in a RAW converter you do see that there is enough detail in the highlights (bright overcast for example) to use it.

Hi golfdiesel, I have got it to work on raw images. Basically I take 3 images using the bracket feature set at + and - 2 stops then open them in PS and remove all auto settings from the 3 images select all 3 in HDR merge and let it do its stuff. It works even better with more images typically 7 or more. Hope this helps, but I haven't used the feature much, I must make more of an effort.
Harry

I believe you can get "improved" dynamic range from a single raw file by processing the same raw file two or three times with each processed file biased towards either the shadows, midtones, and highlights, then using hdr to combine the "versions" of the same file.

Don,
I think that's what golf is trying but can't get the HDR to accept them.