D4 tethering with Aperture

My first time tethering.  Aperture recognizes the camera at and pulls in the first frame or two.  After that it either won't pull in more frames but it still recognizes the camera connection.  Other times it recognizes the camera but won't pull in any frames.  I tried several cables to ensure I have a reliable one.  I updated the D4 and software.  Any suggestions for settings or things to try? I'd like to use tethering for a "photo with santa" event this Saturday.  Thanks