mobile shell 3.5 skins help

[nebler]

Hi guys, i have just downloaded the new skins for mobile shell 3.5 from this website
http://www.imarche.net/omnia/index.php

i have dragged the zip file over to the phone(htc copy), and i just get this message.

"the file can not be opened. either it is not signed with a trusted certificate or one of its components can not be found."

i have installed pocket rar like it says.
and i have had the skins work with mobile shell 3

anyone have a clue what to do?

thanks
ben