That error usually shows up when the call to database fails. To see why this is failing, the Message field of the connection object may be of use. Try adding something like:
if(~isempty(conn.Message))
h = errordlg(conn.Message);
uiwait(h)
end
to your compiled application after calling database, where conn is the name of your connection object. This will pop-up an error dialog with the contents of the message to show any error text.
