1.) Was your volume to high? Meaning, is your wort watered down? If you took too much sparge from your MLT to Boil kettle, you would have a very low gravity. I STRONGLY RECOMMEND CHECKING PRE-BOIL GRAVITY!
2.) What about the crush? was it too coarse or was there channeling? The thing is that the recipe or target OG from AHS is assuming some brewhouse efficiency. Yours is likely different, so you should arrive at a different gravity if you have the same volumes. The only way to get the exact same gravity is to either know your efficiency and hit it perfectly, or to know your pre-boil gravity and boil off rate, and adjust the pre-boil gravity as needed. My efficiency is never the same, so I rely on the pre-boil gravity for control.
I am a noob myself, but since I started measuring and controlling to pre-boil gravity, there is never a surprise after the boil. I always hit my intended OG because I know my boil-off rate.
If you'd like to do the same, use this formula:
(conc. pre-boil)*(volume pre-boil) = (conc. post-boil)*(volume post boil)
An example would be I want 5 gallons at OG 1.050. So if my boil off rate is 1 gal per hour, and I will boil for 60 minutes, I know my volume pre-boil will need to be 6 gallons (to end up with 5 after boiling). Now here's the important part - Use the formula above to find the pre-boil gravity needed. In this case it would be:
(conc. pre-boil) = (.050)*(5 gallons) / (6 gallons)
That gives .042 pre-boil concentration or 1.042 pre-boil gravity.
After you have that number, all you have to do is measure what you're putting to the boil kettle from the MLT. Just keep sparging and diluting until you hit 1.042 (or whatever pre-boil gravity you need). Once you boil for 60 minutes, you'll nail the OG you expect. Guaranteed or my name isn't Pangea.