Foreign domain ou-structure to treeview object...expertise needed

Here is my simple script which works fine on my own domain (first one: TreeViewOwnDomain.ps1). Now I want to read foreign domain and use treeview as same way.

Here is also another script which connect foreign domain and read user data (second one: ForeignDomainUserData.ps1).

Can anyone help me?

function Add-Node {
	param ($selectedNode, $name)
	$newNode = new-object System.Windows.Forms.TreeNode
	$newNode.Name = $name
	$newNode.Text = $name
	$selectedNode.Nodes.Add($newNode) | Out-Null
	return $newNode
}
function Get-NextLevel {
	param ($selectedNode, $dn)
	$OUs = Get-ADObject -Filter 'ObjectClass -eq "organizationalUnit" -or ObjectClass -eq "container"' -SearchScope OneLevel -SearchBase $dn
	if ($OUs -eq $null) {
		$node = Add-Node $selectedNode $dn
	} else {
		$node = Add-Node $selectedNode $dn
		$OUs | % {
			Get-NextLevel $node $_.distinguishedName
		}
	}
}
function Build-TreeViewNew {
	param ($tNode, $tDomainDN, $tviewOU1)
	# Tab 1
	$tNode.text = "Active Directory Hierarchy"
	$tNode.Name = "Active Directory Hierarchy"
	$tNode.Tag = "root"
	$tviewOU1.Nodes.Add($treeNode) | Out-Null
	Get-NextLevel $treeNode $tDomainDN
}
Build-TreeViewNew $treeNode "DC=w12,DC=local" $treeviewOU1

$JobEncrypted = Get-Content "C:\Tools\PowershellScripts\Test\encrypted_password_PS.txt" | ConvertTo-SecureString
$JobCredential = New-Object System.Management.Automation.PsCredential($JobUsername, $JobEncrypted)
$SessionX = New-PSSEssion -ComputerName "192.168.xxx.xxx" -Credential $JobCredential -ErrorAction 'SilentlyContinue'
Enter-PSSession -Session $SessionX
$t = Invoke-Command -Session $SessionX -ScriptBlock {
	$tmp = $null
	$t1 = (Get-ADUser Administrator).distinguishedName; $tmp += $t1; $tmp += "`n"
	$t2 = (Get-ADUser Administrator -Properties *).description; $tmp += $t2; $tmp += "`n"
	$tmp
}
Exit-PSSession
$richtextboxOU1.Text = $t