> i had to replace mmcblk1p1 with mmcblk0 and it worked
> mkfs.vfat -F 32 /dev/mmcblk0

Please be careful ! It looks like the disk numbering depends on whether or not there is an external micro-sc-card inserted or not.

On my device /dev/mmcblk0 ist the whole *external* memory card.
/dev/mmcblk1p1 ist the first partition of the *internal* memory card.

So, be warned - know what you do ! There are even different Filesystems on the interal memory card (/dev/mmcblk1p1 is FAT32, /dev/mmcblk1p2 is ext3).

And please be clear *which* memory card is the problem - internal or external (i mean the micro-sd-card slot).