cycleapp

I took my bike which is a Bianchi Oclet to the bike shop to get a new seat post (my current one is too short). So they measured it to be at 27.2. So i got a Ritchey post.
when i got home, I put the new post on the saddle and then greased up the post. I also put some grease i the seat tube. For some reason the post won't fit. Its supposedly the right size, but it takes a lot of effort just to get it close to the min insertion point. I was reading in some bike manuel that you shouldn't force it so i've kinda given up.
my old seat post practically slides all the way in with just gravity pushing it in (or pulling). My new post is lightly powder coated (or so it appears) whereas my old post is smooth (no paint at all). Maybe that makes the difference. Would it be a good idea to get a smaller size post? I am not sure what i should do short of just taking at back to the bike shop and getting either a smaller post or just have them try to install it. any ideas?