Why get-website powershell in ASP.NET MVC only show my site in windows server 2008

See more:

ASP.NET

IIS

PowerShell

MVC

I should manage all website with ASP.NET MVC and PowerShell in IIS, but when I execute this command, it only shows my website

What I have tried:

using (PowerShell PowerShellInstance = PowerShell.Create()) 
{
    PowerShellInstance.AddScript("Get-website");

    var lstSite = PowerShellInstance.Invoke();

    foreach (var psObject in lstSite) 
    {
        result += psObject + "***";
    }
}