Loops and arrays

I am working on an assignment for class. I am supposed to get 25 random numbers to appear in A1:E5, then using arrays and loops, I am supposed to get the same numbers to appear in cells F1:F25.
There are 3 parts to this assignment:
Part 1: fill cells A1:E5 with random integers between 0 - 99
Part 2: fill the two-dimensional array with the values of cells A1:E5
Part 3: fill cells F1:F25 from the two-dimensional array.
Here is my code followed by the issue I am having.

Option Explicit
Dim intTwoDimArray(4, 4) As Integer
Dim intArrayRange As Object
Dim intColumnIndex As Integer
Dim intRowIndex As Integer
Dim intArraySize As Integer
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
For intRowIndex = 1 To 5
    For intColumnIndex = 1 To 5
        Cells(intRowIndex, Chr(64 + intColumnIndex)).Value = Int(Rnd * 100) + 1
    Next intColumnIndex
Next intRowIndex

For intRowIndex = 0 To 4
 For intColumnIndex = 0 To 4
        intTwoDimArray(intRowIndex - 1, intColumnIndex - 1) = Cells(intRowIndex, Chr(64 + intColumnIndex))
    Next intColumnIndex
Next intRowIndex
 
For intRowIndex = 1 To intArraySize
    Cells((intColumnIndex + (intRowIndex * 5)) + 1, "F").Value = intTwoDimArray(intRowIndex, intColumnIndex)
Next intRowIndex
End Sub

I keep getting a runtime error 9 and it highlights " intTwoDimArray(intRowIndex - 1, intColumnIndex - 1) = Cells(intRowIndex, Chr(64 + intColumnIndex))."'
Please help and any and all help is appreciated.