Installation crashes (grub not writeable) on Acer Aspire V5 122P with preinstalled Win8

Think not a bug ... Question is, on which partition should grub set in this EFI-System ... the efi-Partition seems bnot to be the right
or otherwise, how may someone tell this EFI to list Ubuntu and Win8 together.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: ubiquity 2.14.6
ProcVersionSignature: Ubuntu 3.8.0-19.29-generic 3.8.8
Uname: Linux 3.8.0-19-generic x86_64
ApportVersion: 2.9.2-0ubuntu8
Architecture: amd64
CasperVersion: 1.331
Date: Wed Nov 27 19:39:49 2013
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash --
LiveMediaBuild: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MarkForUpload: True
ProcEnviron:
 LANGUAGE=de_DE.UTF-8
 TERM=linux
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)