How did you get to install it? As far as I understood it is only possible manually, and if your system ist seen as suitable for it. I do not have the option to install the 2004 Update and am still stuck with this error. manually checked updates and everything..
EDIT: somehow it worked just after I typed this reply by going to the installer site via google and not the dropbox account page and then installing it from there without downloading the installer first and then starting it