I'm not entirely sure either. With recap 2.6+ and titan 1.24+ it should show.
Do you have any other non-default titan plugins? If the Recap plugin is the only one you've installed other than titan, the dropdown should look like:
Titan Panel
Titan Built-in >
Recap
Auto-hide
Center text
Display on top
Instead of expanding the "Titan Built-in", the Recap plugin should be checkable from the main dropdown.
If it's not there and it shows up on AddOns, my first suspicion would be the xml file is missing or somehow wrong. In the TitanRecap directory should be four files:
localization.lua
TitanRecap.lua
TitanRecap.toc
TitanRecap.xml
It's possible maybe only the .toc got extracted. Redownload the one here:
http://www.wowinterface.com/download...fo.php?id=4007
And reinstall perhaps? If that doesn't work let me know. May be something conflicting.