weird update issue

Hi im having a small issue with updating my psp from 3.71 m33 to 5.00 m33.

I have read the instructions and it seems i have done everything right, i copied the update folder from the 5.00 m33 to psp/game, i tried to get the psp to download the other part 500.pbp and it did that ok, however everytime i ran the installer it said invalid file everytime it checked the 500.pbp file.

So i considered it might of been a bad download of the file and went directly to dark-alexs site and got the 500.pbp from there, but for some reason it did exactly the same thing, so i went back to his site and tried to do a redownload of all files, but it is doing the same thing no matter what i do, any clue whats going on and how to fix this issue?

hey, i have also now tried to go from 3.71 m33 to 3.80 m33 and got the firmware 3.80 from daxs site but for some reason it also says invalid file when it checks the pbp, can`t anyone shed some light on whats happening.