Please see the
Full Tilt Configuration Guide - this explains how to set Full Tilt up to write hands, and how to configure PT3 to import them.
To see if the hand histories are being written, use "My Computer" to view the folder you configure Full Tilt to write them to.
The FAQs linked above have a link to the information about running as Administrator:
ATTENTION: Windows VISTA users, you must read this...
We don't have the resources for telephone support, sorry.
We'll get you sorted out, though.
If you still have trouble after following the links in this post please read the FAQs too:
PT3 Importing FAQ
PT3 HUD FAQ
If you're still stuck tell us what you do have working and we'll give you the next step to check.