Can't convert gif and bmp to jpg?

[Guidance]

D:\Program Files\XnView>nconvert -quiet -o d:\g\_thumbnail\2445.jpg -out jpeg -q 60 -opthuff -rmeta -rexifthumb -gamma 1.5 -ratio -rtype linear -rflag decr -resize 128 -truecolors "D:\dl\RapidQ\Documentation\html\chap9d1.gif"

Error: This picture cannot be written using this format (D:\dl\RapidQ\Document
ation\html\chap9d1.gif)

I'm using nconvert v4.10, and that gif picture looks very well in xnview in fact. Same problem with bmp file.
Below input formats are OK with this command:
jpg, wmf, psd etc.

[Guidance]

While using -ratio, -resize still need two parameters, the other one could be 0.

[xnview]

While using -ratio, -resize still need two parameters, the other one could be 0.

2 parameters is always needed by -resize