Error on installation

[FlaviusNavius]

I have downloaded all the files etc and put them into a folder in Program Files (x86). Whenever I try to run the setup.exe, I get a message saying "This installation package could not be opened. Verify the package exists and that you can access it, or contact the application vendor to verify that this is a valid Windows Installer package."
I'm running Win7 64bit with unmodded RTW BA 1.6.

[Danius]

Read the installation instructions again.

[century x]

Run it as administrator

[FlaviusNavius]

Ok, turns out the .msi was corrupt or something. Now I can start the installer, but while installing it tells me "Source file not found: C:\RSII\RS21.cab. Verify that the file exists and that you can access it".
I'm installing into C:/RSII (all the RTW files have been copied there).

[century x]

Re download everything. You got some corrupt files there. Clean them out then re download