Runas with admin rights

[MAC2979]

$Account = "account"

$Domain = "domainname"

$Password = "password"

$RunCommand = "IE7-Setup.exe /passive"

RunAs($Account, $Domain, $Password, 2, $RunCommand)

I'm trying to use the Runas command to install some software. This actually starts the extraction process but stops when it gets to actually running the install. When trying to run this I'm logged in as a domain user that isn't an administrator, the account I'm passing is a domain admin so has the rights to install, but its not doing so.

Any ideas what I'm doing wrong?

Thanks