I don't quite understand. I am using Stitcher 3.6.1 on a Mac. I have loaded a full panorama of 24 images that have been processed in Photomatix Pro to HDR. I can see them all very clearly to stitch, but when I render to a file, the image is almost completely black. Opening the HDR image files individually shows them to be fine.
 
The HDR files are saved as EXR as HDR files won't import into Stitcher from Photomatix Pro
 
Has anyone any suggestions?

You gotta get yourself version 5.6. It's the first version to deal with HDR images natively. Otherwise, you'll have to render out multiple stitches and then combine the renders with Photomatix.

Oooops!!! That's a typo!! I have version 5.6.1 - which is why I am amazed I am having problems.

I have spoken to the Photomatix Pro guys. My images are comparatively dark, but appear fine in Stitcher. Opening in Photoshop requires a tweak of the 32-bit preview settings and increasing the exposure a couple of stops.
Using the increase exposure function in Stitcher has lightened them enough to make them very white in Stitcher, but when they render I still get a black image.
Any ideas?!

Hi, i'm french guy (sorry for my english)
2 months ago, I 've tested the trial version of Stitcher 5.6
I have exactly the same problem
HDR images stitched in  Stitcher produced a HDR panorama that is very dark when I open it with Photomatix. (but the original HDR images are normal and luminous)
I've a send a mail to the technical team (06/22/2007) about this problem

I've found that it seems to be to do with the blending option!
Using Linear or Morph i get a result that is black in photomatix & PS but tonemaps correctly.
In Smart i get a black empty file which is basically empty.
If i try and use external blending like enblend3 nothing happens.
 
I can load in both HDR and EXR files fine though.
 
Images look dark in the window but nothing that i wouldnt expect normally from an HDR preview!