ITunes 11.3 some things add to library and some don't

Question

I have iTunes 11.3.1 (2) (64 bit) and a Mackbook Pro 13" (early 2011 model) OS X 10.9.4. I moved my music, audiobooks, movies, podcasts, etc to a home server (Seagate Central) and created a new library. I was able to add my ring tones to iTunes as well as my audiobooks and about 600 of my songs. Some songs add and some don't. Doesn't seem to be rhyme or reason. I've imported m4a, mp3, m4p. The items that have imported and am trying to import come from the same iTunes Media/Music folder. I've tried adding both by folder and by individual file. I've also right-clicked a song and selected to open in iTunes and nada. I've also checked the Recently Added playlist and nothing is there as well. These same songs played when they were stored on my Macbook. I don't get it. I'll see a millisecond flash of the album but nothing happens. The only common factors I can see is that if it will let me play it in the finder it will let me add to iTunes. Also, it seems that 'older' stuff I added from CD from my older iPod days doesn't add. For kicks, I tried to copy and paste an album back to my MBP and it says I don't have permission but that happens with both ones that show up in the program and ones that don't. I'm the admin on both my laptop and the server. Grr. HELP!
PS: When I use Seagate's remote site I can listen to songs that won't play in my Finder or add.

Answer 1

I haven't seen this issue before but I have seen lots of posts here about issues with using iTunes with NAS.  General rule of thumb is iTunes is not guaranteed to play well with NAS.  For some it does, for others not.
My understanding is NAS uses its own software to interface with the computer's software.  This could well have been designed with Windows in mind and the drive you are using may be formatted NTFS for Windows and iTunes is having to trust the software 100% for interfacing.  Perhaps your files have illegal characters for Windows naming convention.
Remember the game where people sit in a long row and whisper a message from one end to the other, then compare the results which almost invariably have been garbled in transmission? That's iTunes and your files over NAS.
Maybe some of this is iTunes fault but if you take this issue to an Apple Store I bet they will ask you why you aren't using a plain external hard drive.  If you use third party hardware then it is up to the vendor (who likely sells 95% to PC users) to ensure the interface works.