Switches work for Command line, but not Powershell

I have a Flash Player install that is an .exe file.  If I put

install_flash_player_13_active_x.exe -install

at the command line, it installs it completely silently.  However

$result = Start-Process -Wait -FilePath 'C:\install_flash_player_13_active_x.exe' -ArgumentList '-install' -PassThru

brings up the user interface and I have to click through it to keep going.  Am I going to just have to make it a cmd call in Powershell to make it work?