How can i save the highest Unique task ID in a project level custom field.

[BVOPP]

Sorry i was not clear enough in my previous quote. But i already managed, the custom fields on Project level are available. The code i created to check if task have been added:

Sub Max_UniqueID()
    
    Dim t As Task
    Dim Max_UniqueID As Long
       
    MsgBox "This was the Max UniqueID in the project before: " & ActiveProject.Text1
       
    For Each t In ActiveProject.Tasks
        If Not t Is Nothing Then
           If t.UniqueID > Max_UniqueID Then Max_UniqueID = t.UniqueID
        End If
    Next t
    
    If Max_UniqueID <> ActiveProject.Text1 Then
        MsgBox "Please check there are tasks added to the plan, previous: " & ActiveProject.Text1 & " Now: " & Max_UniqueID
        ActiveProject.Text1 = Max_UniqueID
    End If
 
End Sub