Go to
www.submitservices.com and download a free copy of webposition gold if you don't already own it. Do a comparision between your site and the one you are ranking under. It will tell you exactly what you need to do. It could be lots of things such as relevency, frequency of the keyword in the body, the use of the keyword in a hyperlink etc. Perhaps an alt tag or two may need to be added. I would say you should try and rank higher for different words or phrases. I had to read your site to see what the word was or what it meant. Try and think like someone out there trying to find your site and what you have to offer and think of everyday use words that will work. Words that If I were just sitting at my computer might type in the search bar of a search engine.
Nicely done site by the way,
Dmcgill