exporting to WAV

Is it possible to export multiple files to WAV in 24 bit rather than only 16 bit which is what it allows me do to. I have the latest Audacity on two computers, one is Windows XP, the other is Windows 7. Is there something I am missing ?

Select “other uncompressed files” as the Export format, then click the “Options” button and set “Header” for “WAV (Microsoft)” and the “Encoding” as “Signed 24 bit PCM”.