That sounds famaliar about the version of DSS, I seen somwher that there was an addition to DSS that supported RAW images for newer cameras or something along those lines.
The photos are widefield shots through an 18-55mm lense on a tripod. DSS stacks the JPEGs with no dramas even though the camera is on a fixed mount, so I would assume that it would also have no issues stacking the same in RAW format but the final black strip image has me stuck.