Keine Methode mit dem Namen op Addition beim Ausführen eines PS Skriptes

Fehler beim Aufrufen der Methode, da [System.Management.Automation.PSObject] keine Methode mit dem Namen "op_Addition" enthält.  

Major  Minor  Build  Revision
-----  -----  -----  --------
4      0      -1     -1      

[void][System.Reflection.Assembly]::Load("Microsoft.SharePoint, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c")   
# get local farm
Add-PSSnapin Microsoft.SharePoint.PowerShell
$farm = [Microsoft.SharePoint.Administration.SPFarm]::Local
# get web services from local farm
$websrvcs = $farm.Services | where -FilterScript {$_.GetType() -eq [Microsoft.SharePoint.Administration.SPWebService]}
# format for .csv file output
$outputToCSV = @()
function CheckedOutItems()
{
    # get all web services available in the farm   
    foreach ($websrvc in $websrvcs) {
        # retrieve web applications
        foreach ($webApp in $websrvc.WebApplications) {
            # now get site collections from the web application
            foreach ($site in $webApp.Sites) {
                # process each web site
                Try {
                    foreach ($web in $site.AllWebs) {
                         $siteUrl = $web.Url
                         $siteName = $web.Title
                         $siteUserCnt = $web.AllUsers.Count
                         $PimarySiteAdmin = $site.Owner.Name
                         $SecondarySiteAdmin = $site.SecondaryContact.Name
                         $siteusage = $site.Usage.Storage/1MB
                         $Hits = $site.Usage.Hits                       
                         $Created = [datetime]$web.Created
                         $LastModified = $Web.LastItemModifiedDate
                         $SnapShot = (get-date)
                         $LastUpdate = ($SnapShot – [datetime]$LastModified)

                         $outputToCSV += New-Object PSObject -Property @{"Site Title" = $siteName; "Url" = $siteUrl; "Primary site collection admin"= $PimarySiteAdmin;   
                                                                        "Secondary site collection admin"=$SecondarySiteAdmin; "Total Users" =$siteUserCnt;"Size" = $siteusage;   
                                                                        "Date Last Modified" = $LastModified; "Days Last Update" = $LastUpdate; "Hits" =$Hits; "Date Created" =$Created  
                                                                        }
                                        $file_date = get-date -format M-d-yyyy
                                        $file_name = "$env:USERPROFILE\Desktop\NoCheckedInVersion"+ $file_date + ".csv"  
                                        $outputToCSV | ConvertTo-Csv -notype > $file_name

                } # end $site.AllWebs loop
            } # end Try statement 
            # General catch exceptions
            Catch {
                    "General Exceptions caught: " >> "$env:USERPROFILE\Desktop\errorlog.txt"  
                    $_.Exception.Message >> "$env:USERPROFILE\Desktop\errorlog.txt"  
            }# end general catch statement
            }
        }
    }
}
# Make a call to the function
CheckedOutItems