Bad output format 'jxr'

[monilgandhi]

I am trying to convert a png file to 'jxr' on 64 bit linux machine. I can convert the png to jpeg. But jxr is giving me an error
Bad output format 'jxr'

Here is the command i use for jxr
nconvert -out jxr test.png
Bad output format 'jxr'

and here is the command for jpeg which seems to be running fine
nconvert -out jpeg test.png
** NCONVERT v5.91 (c) 1991-2011 Pierre-E Gougelet (May 12 2011/11:09:45) **
Version for Linux x86 (X11) (All rights reserved)
** This is a freeware software (for non commercial use)

Conversion of test.png into test.jpg OK

Does anyone know what is going wrong here?

[xnview]

Available in 6.05, please wait next release...