Sansa Connect with Winamp

I’m trying to add files to my Sansa Connect using either the latest version of Winamp Pro or Windows Explorer (I’m using Vista, but I have access to XP too). When I try to add files by dragging and dropping from My Music to the Music folder in the Sansa, it shows a loading box, but after several minutes of trying just one song, nothing happens. When I try to drag files from My Media Library in Winamp to Sansa (under Portables), it says “Error In Insert.” What to do?