Simple Powershell - what am I doing wrong?

Question

OK, so this works:
Set-CMDistributionPoint -SiteSystemServerName DP01.test.com -EnablePxeSupport $True -AllowRespondIncomingPxeRequest $False -ComputersUsePxePassword $PXEsecure -EnableUnknownComputerSupport $True
I need this to work:
# Getting distribution point network path
$CM_DP = Get-CMDistributionPoint -DistributionPointGroupName "Test DP Group"
$CM_NOSP = $CM_DP.NetworkOSPath
# Need to change the DP Path to remove the starting \\
$CM_DPN = $CM_NOSP.TrimStart("\\")
#Prompt for PXE Password
$PXEsecure = Read-Host “Enter desired PXE boot password” -AsSecureString
#run DP Configuration
foreach ($CMDistributionPoint in $CM_DP)
{Set-CMDistributionPoint -SiteSystemServerName $CMDistributionPoint -EnablePxeSupport $True -AllowRespondIncomingPxeRequest $False -ComputersUsePxePassword $PXEsecure -EnableUnknownComputerSupport $True}
It doesn't and I cant work out why!?

Answer 1

There was a typo:
# Getting distribution point network path
$CM_DP = Get-CMDistributionPoint -DistributionPointGroupName "Test DP Group"
$CM_NOSP = $CM_DP.NetworkOSPath
# Need to change the DP Path to remove the starting \\
$CM_DPN = $CM_NOSP.TrimStart("\\")
#Prompt for PXE Password
$PXEsecure = Read-Host “Enter desired PXE boot password” -AsSecureString
#run DP Configuration
foreach ($CMDistributionPoint in $CM_DPN)
{Set-CMDistributionPoint -SiteSystemServerName $CMDistributionPoint -SiteCode EUR -EnablePxeSupport $True -AllowRespondIncomingPxeRequest $False -ComputersUsePxePassword $PXEsecure -EnableUnknownComputerSupport $True}
But I still get an error for this:
'Cannot access a disposed object.'