I always give first partition 20 M, How big is your uImage? Please, double check it.
And I always format second partition. You choose the file system (ext2, ext3, ext4, vfat, whatever one kernel recognizes)
and I copy the u-boot-noparding.bin using this command line:
$ sudo dd if=u-boot-no-padding.bin of=/dev/sdX bs=1K seek=1
And for uImage I use this command line:
$ sudo dd if=uImage of=/dev/sdX bs=1M seek=1
What are you using? Please, paste over here the log.