So I have a CSV file with userids, I am importing those IDs, getting computers they are listed as ManagedBy, and want to output it to a text file. But for some reason I'm getting this error

Out-File : Cannot validate argument on parameter 'Encoding'


$UserID = @()
$Asset = @()

Import-Csv "C:\Scripts\FY18 Deskside Tracking Proactive Refresh.csv" |`
ForEach-Object {
Clear-Variable -Name UserID,UserAsset
    $UserID  = $_.UserID
    $Asset  = $_.Asset      
 $UserAsset = (Get-ADComputer -Filter "ManagedBy -eq '$UserID'").SamAccountName
 Write-Output $UserID $UserAsset | Out-File -filepath "C:\Scripts\FY18.txt" $UserAsset $username -Append
  }