macbook iphoto to iphone 5c - some photos don't transfer

I got an iPhone 5c last night. This is my first smartphone of any kind, although my partner has an iPhone 5 which I have used here and there, and I did have an old iPod Touch for a few years.

I also have a MacBook from 2006, running OS 10.6, and I would like to transfer a handful of existing photos from my MacBook to my iPhone to use as background photos. I created an album called "iPhone" in iPhoto, put the pictures in it, set iTunes to sync only selected albums, events, etc., and selected only that album "iPhone" - I don't want iTunes to try to put my entire photo library on my iPhone. Then I hit apply, and sync. However, only 4 of the 6 photos will transfer successfully. I tried unmounting the iPhone as well, to see if that final sync would change anything, but no luck.

The two photos that won't transfer were photos taken with my partner's iPhone 5, which I transferred directly to iPhoto by plugging his phone into my computer (probably over a year ago). I am wondering if the fact that they belonged to a different iPhone is the reason - or maybe because that phone was running iOS 6 at the time? Or could it be to do with my MacBook being so old? Maybe this is an issue of incompatibility, or maybe it is an iOS 7 bug? My 5c is also refusing to acknowledge my MacBook through bluetooth. Any ideas? Thanks

Oh sorry - I just realised that one of the photos that won't transfer was taken with our Canon DSLR - so that throws my compatibility theory out the window.