"some.PDF" was not copied...

"some.PDF" was not copied to the iPad "my iPad" becasue it could not be found.

So where's it looking for it? How about a clue so I can fix it. Why did this happen? Is it going to happen every time I delete or move some files?

Just click "Do not warn me again"? I'll always no it's a little wonky, I can't stand that. After twenty-nine years of daily Macintoshing I am struggling with the new "The Apple way or no way" phylosophy Copertino is shoving down our throats (but I like the advantages.)

Can't find any Apple documentation on this. Can't find anything Googling.

Retina laptop running 10.8.1; six month old iPad running 6.0.1; iTunes 11.0.1 (12)

Thanks in advance,

Sam