Yes my AOE is perfectly working (but not when I have Wars of Liberty installed I think it's normal).
And I tried lauching the age3y.exe and same error : Could not load DATAPY.BAR
Hm, that's really weird, I mean, really really weird.
Which AoE3 version do you have, the CD or Steam one? Also, are you entirely
sure that the folder in which you installed WoL also
contains the base AoE3 files (that is, are you sure that you did not
install WoL in a blank
Could you take a screenshot of the folder in which you installed WoL, please?