iTunes 11.5.1? The current version is 11.2.1
On the Mac using Mavericks, contact sync using iTunes was not available with OS X versions 10.9 through 10.9.2 (contact sync was only by iCloud). Version 10.9.3 returned the "Info" page of iTunes and again made contact sync using iTunes possible on a Mac. If you have OS X 10.9.3 and iTunes 11.2.1, have you checked the settings on the Info page of iTunes (after you connect your phone)?