For instances like this, did you change the system date to around the time of the distribution? So, for instance let's say the event happened from... January 1st to February 1st, is your console's date within that time frame? It can either be that, or you have a faulty distribution ROM, in which case I would suggest finding that same ROM from another source.
EDIT: Second solution. If you're knowledgable with the software Pokegen you can use that to load your Pokemon game's save file and then, with the appropriate event's .PKM files (Google that) you can manually upload the event Pokemon into your game.