You don't specify a great deal of information, for example, what bios you are using? You may not think that matters, but if you followed the xbox scene tutorial whereby the name of the original dash must be changed, yet you are running a 'ybox' or 'evox' bios which looks for either of the aforementioned dash names (yboxdash.xbe and evoxdash.xbe respectively) then the name of the original dash does not need to be altered and the actual evolution dash should be named accordingly.
More than likely is that you have burned the ISO incorrectly, if I were you I'd read about burning on ISO on xbox scene, double check that the ISO contains the correct dash name and the evox.ini which ir correct. Some people have had trouble with the autoload function, but I can't see that being it.
Good Luck, TeMpTeD