I'm not sure you've provided quite enough information. I doubt I can help much, but I'll ask the questions that have occurred to me anyways for clarification.

Are you sure that you have enough space remaining on your iPod? (I would imagine so; 133 songs isn't all that much.)

What exactly are you doing? You are dragging the songs from your iTunes library into your iPod playlist and syncing your iPod up with that playlist, right?

Can you play the songs directly from your iTunes library?

What kind of error messages (if any) are you getting?