Function not Returning Data - function

Question

I am using PowerShell to compare the file count and size (per file extension) in 2 separate directories.
$User = $env:username
$pwd = pwd
clear
write-host "`n"
write-host "`n"
write-host "`n"
write "The current user is: $User"
write-host "`n"
write "The current path is: $pwd"
write-host "`n"
write-host "`n"
write-host "`n"
write "We need to know the following information:"
write "`n"
write "`n"
$UserDesktopPath = Read-Host "New PC User Desktop Path" # This should be the new PC Desktop Path
$UserDocumentPath = Read-Host "New PC User Document Path" # This should be the new PC Document Path
$USBDesktopPathServer = Read-Host "USB User Desktop Path" # This should be the USB User Desktop Path
$USBDocumentPathServer = Read-Host "USB User Document Path" # This should be the USB User Document Path
clear
write-host "`n"
write-host "`n"
write-host "`n"
write "This is the results for your Desktop Folder Paths:"
write-host "`n"
$folder_new = Get-ChildItem -Recurse -path "$USBDesktopPathServer" # Recurses the New PC Desktop
$folder_old = Get-ChildItem -Recurse -path "$UserDesktopPath" # Recurses the USB Backup Desktop
Compare-Object -ReferenceObject "$folder_new" -DifferenceObject "$folder_old" # Compares the two folders for the path to identify discrepancies
write-host "`n"
write "This is the results for your Documents Folder Paths:"
write-host "`n"
write-host "`n"
write-host "`n"
$folder_new1 = Get-ChildItem -Recurse -path "$UserDocumentPath" # Recurses the New PC Documents
$folder_old1 = Get-ChildItem -Recurse -path "$USBDocumentPathServer" # Recurses the USB Backup Documents
Compare-Object -ReferenceObject "$folder_new1" -DifferenceObject "$folder_old1" # Compares the two folders for the path to identify discrepancies
write-host "`n"
write-host "`n"
write-host "`n"
write "Now we shall compare file sizes of your Documents:"
write-host "`n"
write-host "`n"
write-host "`n"
write-host "`n"
function doc{
$DirectoryDocuments = "$USBDocumentPathServer", "$UserDocumentPath"
foreach ($Directory in $DirectoryDocuments) {
Get-ChildItem -Path $Directory -Recurse |
Where-Object {-not $_.PSIsContainer} |
Tee-Object -Variable Files |
Group-Object -Property Extension |
Select-Object -Property #{
n = "Directory"
e = {$Directory}
},
#{
n = "Extension"
e = { $_.Name -replace '^\.' }
},
#{
n = "Size (MB)"
e={ [math]::Round( ( ( $_.Group | Measure-Object Length -Sum ).Sum / 1MB ), 2 ) }
},
Count
$Files |
Measure-Object -Sum -Property Length |
Select-Object -Property #{
n = 'Extension'
e = { 'Total' }
},
#{
n = 'Size (MB)'
e = { [math]::Round( ( $_.Sum / 1MB ), 2 ) }
},
Count
}
}
When using the ISE and calling dtop I get the correct return:
PS C:\Users\Michael Nancarrow> dtop
Directory Extension Size (MB) Count
--------- --------- --------- -----
D:\Deployment Kit\Test\Desktop2 txt 0 1
Total 0 1
D:\Deployment Kit\Test\Desktop1 txt 0 11
Total 0 11
Yet when run in the script, it does not return any value. I have attempted to call a function write $tst which runs dtop and that does the same (writes null).
Furthermore, I have removed the { so it does not run as a function, and it operates without an issue. My concern is perhaps the -Path file cannot be parsed at the same time as the input - meaning: when I call dtop from ISE it already has the $Directory variable stored in memory.
Are there any obvious errors here? I am rather new to PowerShell and am unsure where the mistake lies.