Problem to load the adapter
Make sure to unblock all files for the Null adapter if windows set them as blocked.
If the BizTalk Server is a 64-bit server you might need to change the AdapterReg.reg file. You can also download it and replace the original file.
The change is the HKEY_CLASSES_ROOT\CLSID\ to HKEY_CLASSES_ROOT\Wow6432Node\CLSID\ in the file AdapterReg.reg. If you aldredy installed it than run Install.exe again and uninstall and then install it again with this new file.