Yep sounds like you have the same sticking point as me. It sounds like you did a lot of things right. What's missing is the emotional spiking, e.g. introducing a sexual context, inuendo, etc, to the conversation and initiating physical escalation.

If you don't do this within a certain time frame you will start sinking into the quicksand of a friendly conversation and she won't be turned on. Then when you try to intiate physical escalation she'll reject and you'll feel like total shit wondering if she ever liked you in the first place.

EDIT: I should add that spiking has to be balanced with comfort and normal conversation. I'm sure I scared a girl off recently because I think I put her under too much pressure by spiking too much.

When you're on the learning curve the pendulum tends to swing too far one way then the other until you get it just right.