Why is my Invoke-Command failing? - powershell

Question

I am putting together a script that will check all of my web servers certificates so that I can monitor when they are set to expire. When the script goes to execute the Invoke-Command I am getting this error:
Here is my code:
Import-Module WebAdministration
$results = #()
$ou = 'OU=test,OU=test,OU=Servers,DC=contoso,DC=com'
$subtree = Get-ADOrganizationalUnit -SearchBase $ou -SearchScope Subtree -filter * | Select-Object -ExpandProperty DistinguishedName
ForEach($dn in $subtree){
$servers = Get-ADComputer -Filter * -SearchBase $dn | select Name
$results += $servers
}#ForEach($dn in $subtree)
$scriptBlock = [scriptblock]::Create({
Import-Module WebAdministration; Get-ChildItem -Path IIS:SSLBindings | ForEach-Object -Process `
{
If($_.Sites){
$certificate = Get-ChildItem -Path CERT:LocalMachine/My |
Where-Object -Property Thumbprint -EQ -Value $_.Thumbprint
[PSCustomObject]#{
Sites = $_.Sites.Value
CertificateDNSNameList = $certificate.DnsNameList
CertificateNotAfter = $certificate.NotAfter
}#[PSCustomObject]
}#If($_.Sites)
}#Import-Module
})#ScriptBlock
ForEach($server in $results){
Invoke-Command -ComputerName $server -ScriptBlock $scriptBlock | Select Sites,CertificateDNSNameList,CertificateNotAfter,PSComputerName #ScriptBlock
}#ForEach($server in $results)
Now, If I take the following line out of the loop and replace $server with an actual server name, I get the results I am looking for:
Invoke-Command -ComputerName ServerName -ScriptBlock $scriptBlock | Select Sites,CertificateDNSNameList,CertificateNotAfter,PSComputerName
Any ideas what I am doing wrong?

Answer 1

Your Results-Array is not an array of string, it is an array of object. Each object have the attribute name. Change your last ForEach-Loop into this and your script will work:
ForEach($server in $results){
Invoke-Command -ComputerName $server.name -ScriptBlock $scriptBlock | Select Sites,CertificateDNSNameList,CertificateNotAfter,PSComputerName #ScriptBlock
}#ForEach($server in $results)

Answer 2

It looks to me like "select Name" is returning an object rather than a string. Try changing the line that fetches the servers to this:
$servers = Get-ADComputer -Filter * -SearchBase $dn | select -ExpandProperty Name