[playlist~] problem

I am using a [playlist~] to trigger soundfiles on pressing number buttons corresponding to each soundfile. However, two things are happening that I don't quite understand:

1) When I press button 1 to trigger the first soundfile this error is printed: "sfplay~: no open file" Pressing button 2 plays the first soundfile in the buffer.

2) When a new file is successfully triggered it interrupts the currently playing file. I would like each file to play in full, without a new sound file interrupting. How can I do this?

Thanks,
Peter