Cannot find type [Microsoft.SharePoint.SPSite]: make sure the assembly containing this type is loaded

I'm trying yo Run this script ps1 from C# code but it returns me the following error where trigger "pipeline.Invoke()";

    InitialSessionState iss = InitialSessionState.CreateDefault();
    PSSnapInException warning;
   // iss.ImportPSSnapIn("Microsoft.SharePoint.PowerShell", out warning);

    Runspace runspace = RunspaceFactory.CreateRunspace();

    Pipeline pipeline = runspace.CreatePipeline();
    // open it
    runspace.Open();

    pipeline.Commands.AddScript(@"C:\Users\Administrator\Desktop\Untitled2.ps1");
    try
    {
        pipeline.Invoke();
    }
    catch (Exception ex)
    {
        throw ex;
    }
    //pipeline.Commands.Add("Get-Process");

    // execute the script
    PSObject bob;
    Collection<PSObject> results = pipeline.Invoke();

    // close the runspace

    runspace.Close();

    // convert the script result into a single string

    StringBuilder stringBuilder = new StringBuilder();
    foreach (PSObject obj in results)
    {
        stringBuilder.AppendLine(obj.ToString());
    }

    return stringBuilder.ToString(); 

POWERSHELL

#Add SharePoint PowerShell SnapIn if not already added 

 Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue 



if ((Get-PSSnapin "Microsoft.SharePoint.PowerShell" -ErrorAction SilentlyContinue) -eq $null) { 
        Add-PSSnapin "Microsoft.SharePoint.PowerShell" 
    } 


$site = new-object Microsoft.SharePoint.SPSite("http://sp2010devid/sites/esercizi3");  
$ServiceContext = [Microsoft.SharePoint.SPServiceContext]::GetContext($site);  

#Get UserProfileManager from the My Site Host Site context 
$ProfileManager = new-object Microsoft.Office.Server.UserProfiles.UserProfileManager($ServiceContext)    
$AllProfiles = $ProfileManager.GetEnumerator()  

foreach($profile in $AllProfiles)  
{  
    $DisplayName = $profile.DisplayName  
    $AccountName = $profile[[Microsoft.Office.Server.UserProfiles.PropertyConstants]::AccountName].Value  


    #Here goes writing Logic to your SharePoint List + Check if account already existing in the SharePoint list then ignore writing.......
    write-host "Profile for account ", $AccountName 


}  
write-host "Finished." 
$site.Dispose()