Copy sheet to text file with specific template

[BKChedlia]

I want to copy sheet to text file with specific template, I defined a range but the problem is my code begins in A3 instead of A2 and don't stop to LastRow so it bring empty rows
and skippes even numbers it means rows A2, A4,A6... not copied

Option Explicit

 Sub txtFile()
 
  Dim strPath As String
  Dim fso As Object
  Dim ts As Object
  
   Dim wsDest As Worksheet
   Set wsDest = Sheets("Filter FS")
   wsDest.Select
  Set fso = CreateObject("Scripting.FileSystemObject")
  
  Dim cellAimsID As Variant
  Dim cellAmount As Variant
  Dim cellCurrencyISO As Variant
  Dim cellReason As Variant
  Dim cellExpiryDate As Variant
  Dim FirstRow As String
  Dim LastRow As String
  
  Dim a As Range, b As Range, cell As String, rng As Range
  Set a = Selection
  Set ts = fso.CreateTextFile("C:\Users\cben\Documents\BKC\FinancialSecurity\test11.txt", True, True)
  ' for each cell in the worksheet create a line in text fil
 FirstRow = wsDest.UsedRange.Rows(1).Row
 LastRow = wsDest.Range("A" & Rows.Count).End(xlUp).Row
 Set rng = wsDest.Range("A2:A" & LastRow)
  For Each a In rng
cellAimsID = a.Cells(a.Row, 1)
cellAmount = a.Cells(a.Row, 2)
cellCurrencyISO = a.Cells(a.Row, 3)
cellReason = a.Cells(a.Row, 4)
cellExpiryDate = a.Cells(a.Row, 5)
  
'AimsID, Amount, Currency, Reason, ExpiryDate are the name of columns in worksheet
  ts.WriteLine (Chr(9) & "cases" & ": [")
  ts.WriteLine (Chr(9) & "{")
  ts.WriteLine (Chr(9) & "AimsID:" & cellAimsID & ",")
  ts.WriteLine (Chr(9) & "Amount:" & cellAmount & ",")
  ts.WriteLine (Chr(9) & "CurrencyISO:" & cellCurrencyISO & ",")
  ts.WriteLine (Chr(9) & "Reason:" & cellReason & ",")
  ts.WriteLine (Chr(9) & "ExpiryDate:" & cellExpiryDate & ",")
  ts.WriteLine (Chr(9) & "}" & ",")
 
  Next
 ts.Close
   
End Sub

this is the end result :
cases: [ {
AimsID:69210794,
Amount:EUR,
CurrencyISO:30000,
Reason:0,
ExpiryDate:30.09.2015,
},
cases: [
{
AimsID:86917526,
Amount:MXN,
CurrencyISO:,
Reason:1,
ExpiryDate:22.06.2016,
},
cases: [
{
AimsID:,
Amount:,
CurrencyISO:,
Reason:,
ExpiryDate:,
},
cases: [
{
AimsID:,
Amount:,
CurrencyISO:,
Reason:,
ExpiryDate:,
},