Transferring voice memos to the iphone

I have some voice memos backed up on my MacBook that I would like to transfer to my iphone. In iTunes I have selected the option to include the voice memo playlist, but not all voice memos get transferred. For example, only 11 of the 18 in my playlist are transferred. Any ideas on how I can easily get them all synced up without having to purchase third party software like diskaid?

Thanks...