Powershell to list all machine with Bitlocker Enabled

I'm try to get a list of full list of machines that also identifies if bitlocker ins enabled.

The following is a script that I was hoping to work however line 53
"if ($computer.name -match ('(' + [string]::Join(')|(', $bitlockerenabled) + ')'))"
 throws:

"Exception calling "Join" with "2" argument(s): "Value cannot be null.
Parameter name: value"
At C:\Users\big.bob\Documents\New Users Scripts\Test4\BitLocker_Data.ps1:5
3 char:49
+     if ($computer.name -match ('(' + [string]::Join <<<< (')|(', $bitlockeren
abled) + ')'))
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : DotNetMethodException"
#
#
# NAME: Get-BitlockerComputerReport.ps1
#
# AUTHOR: Jan Egil Ring
# EMAIL: jan.egil.ring@crayon.com
#
# COMMENT: Script to retrieve BitLocker-information for all computer objects with Windows 7 or Windows Vista in the current domain.
#
#          The information will be exported to a CSV-file containing the following information:
#          -Computername
#          -OperatingSystem
#          -HasBitlockerRecoveryKey
#          -HasTPM-OwnerInformation
#          
#          Required version: Windows PowerShell 1.0 or 2.0
#          Required snapins: Quest.ActiveRoles.ADManagement
#          Requried privileges: Read-permission on msFVE-RecoveryInformation objects and Read-permissions on msTPM-OwnerInformation on computer-objects (e.g. Domain Admins)
#          
#          For more information, see the following blog-post: http://blog.powershell.no/2010/10/24/export-bitlocker-information-using-windows-powershell 
#      
# You have a royalty-free right to use, modify, reproduce, and
# distribute this script file in any way you find useful, provided that
# you agree that the creator, owner above has no warranty, obligations,
# or liability for such use.
#
# VERSION HISTORY:
# 1.0 24.10.2010 - Initial release
#  
#
 
#Custom variables
$CsvFilePath = "C:\BitLockerComputerReport.csv"
 
#Export computers not Bitlocker-enabled to a CSV-file
$BitLockerEnabled = Get-QADObject -SizeLimit 0 -IncludedProperties Name,ParentContainer | Where-Object {$_.type -eq "msFVE-RecoveryInformation"} | Foreach-Object {Split-Path -Path $_.ParentContainer -Leaf} | Select-Object -Unique
$computers = Get-QADComputer -SizeLimit 0 -IncludedProperties Name,OperatingSystem,msTPM-OwnerInformation | Where-Object {$_.operatingsystem -like "Windows 7*" -or $_.operatingsystem -like "Windows Vista*"} | Sort-Object Name
 
#Create array to hold computer information
$export = @()
 
 
foreach ($computer in $computers)
  {
    #Create custom object for each computer
    $computerobj = New-Object -TypeName psobject
     
    #Add name and operatingsystem to custom object
    $computerobj | Add-Member -MemberType NoteProperty -Name Name -Value $computer.Name
    $computerobj | Add-Member -MemberType NoteProperty -Name OperatingSystem -Value $computer.operatingsystem
     
    #Set HasBitlockerRecoveryKey to true or false, based on matching against the computer-collection with BitLocker recovery information
      if ($computer.name -match ('(' + [string]::Join(')|(', $bitlockerenabled) + ')'))
    {
    $computerobj | Add-Member -MemberType NoteProperty -Name HasBitlockerRecoveryKey -Value $true
    }
    else
    {
    $computerobj | Add-Member -MemberType NoteProperty -Name HasBitlockerRecoveryKey -Value $false
    }
     
    #Set HasTPM-OwnerInformation to true or false, based on the msTPM-OwnerInformation on the computer object
     if ($computer."msTPM-OwnerInformation") {
    $computerobj | Add-Member -MemberType NoteProperty -Name HasTPM-OwnerInformation -Value $true
    }
    else
    {
    $computerobj | Add-Member -MemberType NoteProperty -Name HasTPM-OwnerInformation -Value $false
    }
     
#Add the computer object to the array with computer information
$export += $computerobj
 
  }
 
#Export the array with computerinformation to the user-specified path
$export | Export-Csv -Path $CsvFilePath -NoTypeInformation
$error[0]|format-list -force