There are a couple of reasons why imaqhwinfo won't load a registered adaptor DLL. The first is that the DLL is not actually loadable. The most likely cause of this that all of the libraries that the DLL depends on are not present on the system, or are not in the expected location. You can use Dependency Walker to investigate that issue.
The second most likely cause is that the exported functions that imaqhwinfo expects to find are not present. What happens if you try to compile and register the demo adaptor? If the demo adaptor is present, make sure that you are properly exporting all of the functions that the adaptor kit indicates need to be exported. The Dependency Walker tool above can help with that issue as well.