Track cannot be found (ipad-PC i-tunes)

Hi

I am trying to sync the music from my ipad to my PC. Through I-cloud I have managed to add songs from my ipad to my PC. I now want to add some older music from my PC to my Ipad, but am unable to. I have followed the step by step guide, but when I try to drag songs across it says 'file cannot be found'.

Am I missing something? Do I need i-tunes match for this?

Any help would be much appreciated as it's quite frustrating.

Thanks