trajectory validation question

[flims]

I was watching the instruction video by Shawn Carlock again and i decided to follow up his steps inserting all the information he did in my PDA Exbal program to see how to validate the trajectory.

when he mentions the 800yard zero i clicked on table and i got 17.25MOA so that matched like in the DVD. then i went to trajectory validation and i inserted 800yards under 'Target distance', then i clicked on the 'Sight adjustment used' and instead of getting the same figure i got in the table previously, the program displayed 13.257MOA automatically instead of 17.25MOA. i didn't understand why this happend but nevertheless i left it that way and decided i would change it later.

i decided to continue the process by inserting the Impact pt error of +6". when i validated the trajectory it gave a velocity of 2853 which is only off by 1digit since his was 2852. the displayed correction now for 800yds matched that shown in the dvd i.e 16.45moa

when i decided to start the trajectory validation process again but inserting the 'imagined' dialed in distance which the program had given as 17.25 instead of that mysterious 13.257MOA and the 6" error, the program gave me a calculated velocity of 2537ft/s. i then clicked on apply and the dope for 800yards was now 21.75MOA!
can some one explain this to me?
thank you