RAW files from Nikon Coolpix 5400 - are they unsupported by Aperture?

I have recently updated the firmware on my Nikon Coolpix 5400 to version 1.4 in order to get RAW capability. Unfortunately the NEF/RAW files I create are not compatible with Aperture and I get an "Unsupported Image Format" message that may be similar to the one that other users have highlighted in relation to the OSX 10.4.9 update.

I am able to use all images previously imported and also Fine (JPG) images generated by the 5400 as well as RAW images generated by a D70 and a D200.

Message was edited by: Benedict Jenks