Why won't my iPhone 5 sync with my current iTunes library?

I've had my iPhone 5 for a few months now that I've been trying to sync with the iTunes library on my MacBook Pro RD. This is my main iTunes library as well as my main computer so I'm not looking to sync it with any other iTunes anywhere else. Problem is, it won't. When I connect my iPhone to iTunes, the device does show up and I have the option to sync music, videos, etc. but when I check one of these "sync" boxes and click "apply", nothing gets uploaded to my iPhone. I just want to put some songs on my phone and maybe know that I can upload pictures onto it if I ever want.

I seem to have read about others having this problem, but I haven't paid much attention to what they said. Sorry to add another question to the pile if this is indeed a common problem. I just want to know if there's a way to fix this. I haven't tried doing a factory restore or anything of the sort, but I'm open to suggestions.