Likely due to a shortage of domains linking in.
The use of the keyword 'turnstile' in the domain name is no bad thing, but not as important as it once was.
I looked at your site alongside four competitors (turnstile.com; turnstilesecurity.com; ablertech.com; haywardturnstiles.com). By far the most obvious gap between your site and the competition is in the number of domains linking in. You have 5, where high-ranking competitors have anywhere from 20 to 300. And your 5 domains aren't of the best quality (fencebids.com, etc..)
Quality link building is my only answer then, I'm afraid. It's not very original, but it does work!
