Different cats like different kinds of posts. The one you have may not be desirable from his point of view; it could be too short, too wobbly, wrong texture, etc. Try something different. A lot of cats prefer the horizontal or ramp cardboard scratchers; others prefer a tall verticle post with sisal rope rather than carpet. I have a tall pine log bolted to a stand as well as several other choices. One of my cats adored a 4' redwood plank propped up against a wall. Over the years she wore deep, deep groves in it. See articles on scratching and declawing at http://www.littlebigcat.com/index.php?action=library for more ideas.
dr. jean is absolutely right. i bought a carpeted scratching post for woody and she has yet to touch it. i'd catch her scratching the wooden doorways a lot, so i figured she must like wood better. my parents have a homemade scratching post that's just a piece of plywood with a tree branch nailed to it. woody nearly whittled it away to nothing. (i should have known...her name is woody, after all :lol: ) she also likes the corregated cardboard ones. cats are finicky by nature, even when it comes to scratchers.