quick T injection question!

[chestback.livejournal.com]

Ok so I got my friend to do my injection for me today in my butt, but she didn't inject in the upper left or right part of it, she kinda did it in the middle of the butt cheek.  Is that ok?  Why do you need to inject in the upper part?  Does it not absorb as well if you do not? 

Thanks a lot.  I'm new to this stuff so just wanted to figure it out.