I have the same problem with getting a number close. It's all simply fear of rejection. You obviously have solid game with open, transition, and mid-game, so this last little bit shouldn't be too hard for you to surpass. The best way to do get better at closing is the same way you master opening: get a bunch of material, find the ones that best suit you, and run the material on different women till it becomes natural. Just be confident while doing it. Here's some examples:
When you're about to close, say "I gotta go, but let's see how creative you are" and pull out a pad of paper, pen, and hand it to her. If she doesn't write down her number, say "Wow you're not very creative, huh? Let's try this again" and write
_ _ _-_ _ _-_ _ _ _ on the paper and hand it back to her. This is Mystery's work, not mine. All credit goes to the mPAU himself.
Another good one is "Hey I gotta get going, but I would really like to continue this conversation." If you build good report and have a very interesting conversation going, you'll get a number close no problem. I have no idea who I got this from, but I found a similar close on this site with much more detail.
http://www.seductiontuition.com/harmles ... close.html
And remember, it's all just a game my friend.
Havik