aggression(Production Red)

Little Red,my PR,is chasing a hen.I'm not exactly sure why.The hen she chases stays near the flock as we walk around.everytime Lil red gets a chance she'll chance,and often peck her.
I've heard of birds being Flock abandoned/kicked out,but lil reds nowhere near lead hen,and obviously not near rooster placing.

If i'm correct,it's not "Her" job,to do that.The hen she chases is punkish and at the end of pecking order,(Not the very end).

She si very dominate,and has gotten in a fight with 1 hen just about everyday.Unfourtently,that hen has died.
I don't think she likes this bird really,but are there any reasons,any suggestions I could get?

-ThePRfan

 

Yes,they free range like EVERYDAY,unless forsay too much now(Rarely happens),possible bad storms or so.
I am not too sure on the size.Maybe 6-7-8 feet lengthed.And it's not very high,maybe 6-7 feet high.

I have 20 hens,and 1 rooster.

The hen isn't stressed,nor sick.She acts totally normal,and roosts when it's time and everything.

I'm not too bad at figuring stuff like this out,this just is the most difficult situation i've actually had.
I also have 2 long roosts,top and bottom.
Then near the nesting boxes,(which was suppose to be used for getting higher to step in the nest boxes),they use to roost on,it's very short and only maybe 1-2 feet long.
They use the top of the nestboxing to sleep on as well,and the top roost,but never the bottom big 1.

Little red is molting,and I know molting birds hate being touched,and rather be alone.Is thsi what's causing this attitude?