Hi Michael,
I'm pretty sure that you need to add a newer Device Pack to add support for the 7915 and 7916;
Cisco Unified CallManager Device Package 6.1.1 (3113-1)
Release Notes
http://www.cisco.com/web/software/282074299/21536/cmterm-devicepack-6_1_1_3113-1_readme.html
This is the path for the download;
Voice and Unified Communications > Cisco Unified Communications Manager Version 6.1 > Unified Communications Manager/CallManager Device Packages > 6.1(1.3113) > cmterm-devicepack6.1.1.3113-1.cop.sgn
Hope this helps!
Rob