VBA to add Checkboxes Based on Condition in Another Range

I'm needing to add a condition to the following code, but I just can't get the syntax right. I need it to insert checkboxes into column F only when there is data in Column A.

The code in bold is my attempt to add the condition. What am I doing wrong?

Option Explicit
Sub InsertCheckboxes()

 
Sub Test()

Dim LastRow As Long
LastRow = Cells(Rows.Count, 8).End(xlUp).Row

Dim myBox As CheckBox
Dim myCell As Range

Dim Last As Long
Dim i As Integer
Dim cellRange As Range
Dim cboxLabel As String
Dim linkedColumn As String

    Set cellRange = Range("F4:F" & LastRow & "")

    linkedColumn = "Z"

    cboxLabel = ""

    With ActiveSheet
        For Each myCell In cellRange

        For i = Last To 1 Step -1
            If (Cells(i, "A").Value) <> "" Then

                With myCell
                    Set myBox = .Parent.CheckBoxes.Add(Top:=.Top, _
                                                       Width:=.Width, Left:=.Left, Height:=.Height)
    
                    With myBox
                        .LinkedCell = linkedColumn & myCell.Row
                        .Caption = cboxLabel
                        .Name = "checkbox_" & myCell.Address(0, 0)
                        .OnAction = "Mixed_State"
                    End With
    
                    .NumberFormat = ";;;"
                
                End With
            End If
        Next i
        
        Next myCell
    End With


End Sub

thanks!!