HDR w flash

Question

1) Nikon D-200; 105 mm lens; SB-600 speed flash in combination with a lens mounted ring flash.
2) Nikon is mounted on a rack and pinion stand with rotating head.
3) Sample is a highly reflective metal sample exhibiting small cracks and some corrosion.
4) Camera focus, aperture, iso setting and shutter speed remain fixed; stops adjusted using flash exposure.
The reflectivity of the metallic sample makes image capture of surface structure, small cracks and limited areas of corrosion difficult to capture. Seemed like a good option for Photoshop HDR capability.  Have tried bracketed series involving 3 to 11 images.  Histograms suggest the dynamic range is being covered by the image series.  Photoshop reports there is not sufficient dynamic range to build an HDR image.
I read somewhere that Photoshop uses EXIF info when building HDR images.  Are the fixed camera settings keeping Photoshop from building an HDR image?  Should I be looking at something else?
Some sample histograms randomly selected from cropped thumbnail versions of an image series.  I've pushed as far as two stops on either side of the samples shown here (almost all black and almost completely white but Photoshop indicates there is insufficient dynamic range to build HDR in all instances).

Answer 1

Here's the link to the Photoshop Macintosh and Windows forums:
http://forums.adobe.com/community/photoshop/photoshop_macintosh#
http://forums.adobe.com/community/photoshop/photoshop_windows