can't install avast on win 2003 server

Good morning,
I try to install avast on a server with windows 2003 R2 SP2 an i’ve the following error message :
“you have not the autorisation …”
I’m loging with the administrator account.
Thanks

Hi, just an idea, try copying the setup file to a local drive, ie c:\ and run it from there, looks like you are trying to run from a mapped drive, that does not always work.