Unable to create 5 partitions with setenv bootargs

Hello,

Here is my problem:
when I use the command line to create 5 partitions, it does not matter:
setenv bootargs mem=64M console=ttyAMA0,115200 root=/dev/mtdblock2 rootfstype=jffs2 mtdparts=hi_sfc:1M(boot),3M(kernel),12M(rootfs),1M(config),64K(key)

By cons if I use this command line that create me partitons 5:
setenv bootargs mem=64M console=ttyAMA0,115200 root=/dev/mtdblock2 rootfstype=jffs2 mtdparts=hi_sfc:256k(boot)ro,128k(env),128k(conf),3072k(os),12800k(rootfs)

So I do not understand why the first line does not create me 5 partitions but only 3 partitions (boot, kernel, rootfs)

Do you have an idea? My goal is to have the partitions in the same order as the first command line.

Thk you.