I give up. I've been trying to figure this out for nearly two weeks, and I've gone from this almost working code to crashing the database over and over.  If someone could help me I would be forever thankful!

Here's what I've got and what I am trying to do.

I have a table called DirectoryT which contains a DirectoryId Autonumber Primary field, and Text field Directory Name.

I have a Many-to-Many Table (MasterDirectoryT), with a MasterID (Primary field), ParentID linked back to DirectoryT, ChildID linked back to DirectoryT, and a text field FullDirectoryName.

I have a DirectoryQ query that pull it all together (MasterID, ParentID, ChildID, DirectoryName, FullDirectoryName)

The DirectoryT has just the DirectoryName (e.g. Photos, Videos, 2020, 2021)
I was trying to eliminate having to make records such as D:\Photos\2020\, and then duplicating the year for the videos

My code works like I want, until it hits the example above, and there is not telling what kind of crap I get. And since I use the years in multiple other directories, this has made my work all for nothing.

ParentID  ChildID  FullDirectoryName
3  8   D:\01\From HP computer\
137  8   D:\01\From HP computer\

As long as I don't have a DirectoryName I've used before, it works fine.

So now that I've probably bored you to sleep.  Here is my code. If you can help me fix it so that the entries with duplicate years populate right I'll dance a dance of joy!

Code

Private Sub GenerateNameBtn_Click()
    PopulateNameField
End Sub

Sub PopulateNameField()
    If IsNull(DirectoryName) Then Exit Sub
    Dim TargetDirectoryID As Long
    TargetDirectoryID = ChildID ' Replace this with the ID of the directory you want to process
    GenerateFullDirName TargetDirectoryID
    Me.FullDirectoryName = FullDirectoryName ' Update the FullDirectoryName field in the current record
    Me.Refresh
End Sub

Private Sub GenerateFullDirName(ByVal DirectoryID As Long)
    Dim DirectoryName As String
    On Error Resume Next

    ' Replace "DirectoryQ" with the actual name of your query (e.g., "DirectoryQ").
    DirectoryName = DLookup("DirectoryName", "DirectoryQ", "ChildID=" & DirectoryID)

    If IsNull(DirectoryName) Or DirectoryName = "" Then
        FullDirectoryName = ""
    Else
        Dim ParentID As Long
        ParentID = DLookup("ParentID", "DirectoryQ", "ChildID=" & DirectoryID)

        If IsNull(ParentID) Then
            FullDirectoryName = DirectoryName & "\"
        Else
            GenerateFullDirName ParentID ' Recursive call to get the parent directory name
            FullDirectoryName = FullDirectoryName & DirectoryName & "\"
        End If
    End If

    On Error GoTo 0
End Sub