Wubi is downloading file but I have full ISO [duplicate]

I have "ubuntu-12.04.2-desktop-amd64.iso" and my PC has Windows 8 installed. In my previous windows i.e "Windows 7" I used Wubi to install ubuntu 12.04.2 and installed and work correctly. Now I try to install ubuntu 12.04.2 in windows 8 using wubi, it downloads the file.

I have copied both (ubuntu-12.04.2-desktop-amd64.iso and wubi) in the same and empty folder but it didn't work.

Specs:

  • Mobo: Intel DG41WV
  • HDD: Western Digital 500GB
  • OS: Windows 8 Pro
  • RAM: 2GB

It is not recommended to use wubi in Windows 8, so please install Ubuntu on its own partition.

See:

  • Windows installer page on ubuntu.com
  • UEFI page on Ubuntu help wiki