From the MSDN Library:
http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/office97/html/S
EC41.asp

Not sure how familiar you are with ODBC; but if you are getting #N/A as a
result, it is usually because of problems either with the SQL syntax or the
connection string.  There are a few examples of connection strings in the
reference above, but since these are dependent on the database driver used it
is not easy to give an all-encompassing guide on how to write the connection
string.  Best thing I have found is to search the database developer's site
for "connection string" or do a generic net search for "Connection String"
with your db name, e.g. "Connection String Oracle"