I have syslinux-themes-ubuntu installed, but I'm running Precise. I think that means that ubuntu-defaults-image shouldn't look for the directory 'ubuntu-oneiric' but for 'ubuntu-precise'.
I'll try to copy ubuntu-precise to ubuntu-oneiric in /usr/share/syslinux/themes, and see if that solves it.
I have syslinux- themes- ubuntu installed, but I'm running Precise. I think that means that ubuntu- defaults- image shouldn't look for the directory 'ubuntu-oneiric' but for 'ubuntu-precise'.
I'll try to copy ubuntu-precise to ubuntu-oneiric in /usr/share/ syslinux/ themes, and see if that solves it.