Long Select Case Problem

I have a problem with a select case coding not working.

Here is a sample of the long code:

Private Sub Worksheet_Change(ByVal Target As Range)
     
    Application.EnableEvents = False
     
    Select Case Range("R8").Value
         
       Case Sheet2.Range("$A$11")
        
         'E Unit 1'
            Sheet20.Range("B12").Value = Sheet6.Range("B9")
            Sheet20.Range("D12").Value = Sheet6.Range("C9")
            Sheet20.Range("B13").Value = Sheet6.Range("G9")
            Sheet20.Range("D13").Value = Sheet6.Range("H9")
            Sheet20.Range("B14").Value = Sheet6.Range("K9")
            Sheet20.Range("D14").Value = Sheet6.Range("L9")
            Sheet20.Range("B15").Value = Sheet6.Range("O9")
            Sheet20.Range("D15").Value = Sheet6.Range("P9")
            Sheet20.Range("B16").Value = Sheet6.Range("S9")
            Sheet20.Range("D16").Value = Sheet6.Range("T9")
            Sheet20.Range("B17").Value = Sheet6.Range("W9")
            Sheet20.Range("D17").Value = Sheet6.Range("X9")
            Sheet20.Range("B18").Value = Sheet6.Range("AA9")
            Sheet20.Range("D18").Value = Sheet6.Range("AB9")
            Sheet20.Range("B19").Value = Sheet6.Range("AE9")
            Sheet20.Range("D19").Value = Sheet6.Range("AF9")
            Sheet20.Range("B20").Value = Sheet6.Range("AI9")
            Sheet20.Range("D20").Value = Sheet6.Range("AJ9")
            Sheet20.Range("B21").Value = Sheet6.Range("AM9")
            Sheet20.Range("D21").Value = Sheet6.Range("AN9")
            
        'E Unit 2'
            Sheet20.Range("B23").Value = Sheet6.Range("AV9")
            Sheet20.Range("D23").Value = Sheet6.Range("AW9")
            Sheet20.Range("B24").Value = Sheet6.Range("AZ9")
            Sheet20.Range("D24").Value = Sheet6.Range("BA9")
            Sheet20.Range("B25").Value = Sheet6.Range("BD9")
            Sheet20.Range("D25").Value = Sheet6.Range("BE9")
            Sheet20.Range("B26").Value = Sheet6.Range("BH9")
            Sheet20.Range("D26").Value = Sheet6.Range("BI9")
            Sheet20.Range("B27").Value = Sheet6.Range("BL9")
            Sheet20.Range("D27").Value = Sheet6.Range("BM9")
            Sheet20.Range("B28").Value = Sheet6.Range("BP9")
            Sheet20.Range("D28").Value = Sheet6.Range("BQ9")
            Sheet20.Range("B29").Value = Sheet6.Range("BT9")
            Sheet20.Range("D29").Value = Sheet6.Range("BU9")
            Sheet20.Range("B30").Value = Sheet6.Range("BX9")
            Sheet20.Range("D30").Value = Sheet6.Range("BY9")
            Sheet20.Range("B31").Value = Sheet6.Range("CB9")
            Sheet20.Range("D31").Value = Sheet6.Range("CC9")
            Sheet20.Range("B32").Value = Sheet6.Range("CF9")
            Sheet20.Range("D32").Value = Sheet6.Range("CG9")
            
        Case Sheet2.Range("$A$12")
        
         'E Unit 1'
            Sheet20.Range("B12").Value = Sheet6.Range("B47")
            Sheet20.Range("D12").Value = Sheet6.Range("C47")
            Sheet20.Range("B13").Value = Sheet6.Range("G47")
            Sheet20.Range("D13").Value = Sheet6.Range("H47")
            Sheet20.Range("B14").Value = Sheet6.Range("K47")
            Sheet20.Range("D14").Value = Sheet6.Range("L47")
            Sheet20.Range("B15").Value = Sheet6.Range("O47")
            Sheet20.Range("D15").Value = Sheet6.Range("P47")
            Sheet20.Range("B16").Value = Sheet6.Range("S47")
            Sheet20.Range("D16").Value = Sheet6.Range("T47")
            Sheet20.Range("B17").Value = Sheet6.Range("W47")
            Sheet20.Range("D17").Value = Sheet6.Range("X47")
            Sheet20.Range("B18").Value = Sheet6.Range("AA47")
            Sheet20.Range("D18").Value = Sheet6.Range("AB47")
            Sheet20.Range("B19").Value = Sheet6.Range("AE47")
            Sheet20.Range("D19").Value = Sheet6.Range("AF47")
            Sheet20.Range("B20").Value = Sheet6.Range("AI47")
            Sheet20.Range("D20").Value = Sheet6.Range("AJ47")
            Sheet20.Range("B21").Value = Sheet6.Range("AM47")
            Sheet20.Range("D21").Value = Sheet6.Range("AN47")
            
        'E Unit 2'
            Sheet20.Range("B23").Value = Sheet6.Range("AV47")
            Sheet20.Range("D23").Value = Sheet6.Range("AW47")
            Sheet20.Range("B24").Value = Sheet6.Range("AZ47")
            Sheet20.Range("D24").Value = Sheet6.Range("BA47")
            Sheet20.Range("B25").Value = Sheet6.Range("BD47")
            Sheet20.Range("D25").Value = Sheet6.Range("BE47")
            Sheet20.Range("B26").Value = Sheet6.Range("BH47")
            Sheet20.Range("D26").Value = Sheet6.Range("BI47")
            Sheet20.Range("B27").Value = Sheet6.Range("BL47")
            Sheet20.Range("D27").Value = Sheet6.Range("BM47")
            Sheet20.Range("B28").Value = Sheet6.Range("BP47")
            Sheet20.Range("D28").Value = Sheet6.Range("BQ47")
            Sheet20.Range("B29").Value = Sheet6.Range("BT47")
            Sheet20.Range("D29").Value = Sheet6.Range("BU47")
            Sheet20.Range("B30").Value = Sheet6.Range("BX47")
            Sheet20.Range("D30").Value = Sheet6.Range("BY47")
            Sheet20.Range("B31").Value = Sheet6.Range("CB47")
            Sheet20.Range("D31").Value = Sheet6.Range("CC47")
            Sheet20.Range("B32").Value = Sheet6.Range("CF47")
            Sheet20.Range("D32").Value = Sheet6.Range("CG47")
            
   End Select
     
     Application.EnableEvents = True
     
End Sub

No matter what I enter into R8 nothing happens. When I only had a few lines of code it worked when I tested it, so maybe this is just too long, so it can't function.

Perhaps select case is not even the right method. This is what I am trying to do: in cell b12 (sheet20) I want the name of the assessment for unit 1 # 1 returned in cell b13 assessment unit 1 #2 etc etc etc. Problem is there are 8 different names for that assessment depending on the period. So if period one is in R8, I need the assessment for unit #1 #1 period 1 in that cell. Initially I was going to do a nested if formula in cell b12, but you can only nest 7, so I decided to do VBA coding with select case.

So instead of putting a nested if in every cell, I wrote code for every name to appear when period one is selected and then period 2 and so on, but nothing happens.