Debian: plymouth splash screen does not change

on my Debian box, I have installed Plymouth for a splash screen. I have tried updating the theme but everytime I use the commands: /usr/sbin/plymouth-set-default-theme myTHEME and then try to update it with: update-initramfs -u and add the word splash to the /etc/default/grub file and update the grub by: update-grub the theme i get are simple blue and white bars at the bottom of the screen and the word Debian appears. I've tried changing to the default installed themes and still i have the same theme. Is there something I'm not doing to update it properly?