The AttachDebugger method launches the currently registered debugger for this process. Dr. Watson, however, is not supported. ...

The AttachDebugger method launches the currently registered debugger for this process.  Dr. Watson, however, is not supported. 
The method returns a 'generic failure' if it finds an invalid string in the registry key or an integer value that can be interpretted as follows: 
0 - Successful completion.
2 - The user does not have access to the requested information.
3 - The user does not have sufficient privilge.
8 - Unknown failure.
9 - The path specified does not exist.
21 - The specified parameter is invalid.
Other - For integer values other than those listed above, refer to Win32 error code documentation.