It might be a matter of nerves causing you to miss Low 8, but then again, it might be a shooting fault that you have at that station.
I used to have a terrible time with Low 8 because I never really mastered the mechanics of the shot. High 8 was a piece of cake but Low 8 threw me for a loop.
There can be many reasons why your mechanics of shooting Low 8 are faulty, but the only way you are going to run 25's is to first master Low 8.
Some common faults are: stopping the gun, lifting your head, failing to follow through, "cross-sighting" the target, and shooting before you have acquired the proper sight picture.
Some "fixes" may include: changing to a more open stance, keeping your cheek glued to the stock, exaggerating your follow through, concentrating on the sight picture you must see to break the target, and closing the "off" eye.
Some shooters work on Low 8 by starting several steps back from the shooting pad (toward the High House), then as they experience success in hitting Low 8, they gradually move forward until they are back on the pad. You have to be careful not to let your bad habits creep back into your shooting mechanics as you move closer to the pad.
For me, the solution was to face about 30 degrees left of the low house, winding back to just outside the low house window, tightly closing my left eye, then staring intently into the window as I called for the target. This, in effect, turned a low incoming target into a close range crossing target. I'm not recommending this method for everyone, but if other methods have not worked for you, you might try it. Good luck.