iTunes frustration

So my current podfic project has reached a point where I wanted to copy the file to my phone to listen to it in the car. I created an mp3 and copied it to iTunes, then dragged it to my phone. I got a gray file listing with a broken circle next to it--unplayable. I deleted it and re-dragged it, several times over, re-synced my phone several times, no luck whatsoever.

Did some googling, found a number of people with similar problems but no good solutions.
Finally, after half an hour of frustration...I closed iTunes, disconnected my phone, and then reconnected it, thus restarting iTunes. This time when I tried to copy my file it went with no problems at all.