U-Boot error

Nokia-N900:~# u-boot-update-bootmenu
Default bootmenu entry is '/etc/bootmenu.d/20-Maemo5-KP51.item'
Adding bootmenu entry for: Internal Nand

Configuration file: /etc/bootmenu.d/10-Maemo5-2.6.28-omap1.item
Generating u-boot image for kernel 'zImage-2.6.28-omap1'...
Adding bootmenu entry for: 'Maemo 5 with 2.6.28-omap1'

Configuration file: /etc/bootmenu.d/20-Maemo5-KP51.item
Generating u-boot image for kernel 'zImage-2.6.28.10-power51'...
mkimage: Write error on /home/user/MyDocs/bootmenu.img.d/zImage-2.6.28.10-power51: Success
Nokia-N900:~#