Paypal Express Payment Execution - asp.net

Question

I'm developing in vb.net and as of right now I am not using any API's to receive transaction details I have only been using IPN and PDT variables to get my details however I began to notice that, when using Paypal Sandbox to test, after I go through the process of check out, I do receive all the variables of the details but in my test account, there are no transactions shown.
Do I need to be using the REST API in order to actually approve and execute the payment for the transaction in order to complete a transaction? I had assumed that the entire transaction had been completed successful since I was getting all of the details back but now that I noticed there aren't any transactions showing in my account I'm not so sure whats going on?
Here is the code I have been using to view transaction details
Dim authToken As String = "c37yqZU7UdVWesSoipRHFOwB3fFLv1CfOKWz10hqp0ULz6dYKrlCNuxp9d0"
Dim txToken As String = Request.QueryString("tx")
txToken = "2F816064M1280054A" '"6AX4295820157674V" '"5PD1935338742763G" ' '"70Y83841KE749971T" '"74C31896AA9005743""2RY90202U2008611C" '"0F824628H9566062P" '"5ET57654YS955312K" '
Dim strRequest As String = "cmd=_notify-synch&tx=" & txToken & "&at=" & authToken
'Dim Payerinfo As New PayerInfo
'Dim trans As New Transaction
'Dim tra As New PayPal.PayPalAPIInterfaceService.Model.GetTransactionDetailsReq
'post back to either sandbox or live
Dim strSandbox As String = "https://www.sandbox.paypal.com/cgi-bin/webscr"
Dim strLive As String = "https://www.paypal.com/cgi-bin/webscr"
Dim req As HttpWebRequest = CType(WebRequest.Create(strSandbox), HttpWebRequest)
'req.Headers = valHeader
'Set values for the request back
req.Method = "POST"
req.ContentType = "application/x-www-form-urlencoded"
req.ContentLength = strRequest.Length
'Send the request to PayPal and get the response
Dim streamOut As StreamWriter = New StreamWriter(req.GetRequestStream(), Encoding.ASCII)
streamOut.Write(strRequest)
streamOut.Close()
Dim streamIn As StreamReader = New StreamReader(req.GetResponse().GetResponseStream())
Dim strResponse As String = streamIn.ReadToEnd()
streamIn.Close()
If Not String.IsNullOrEmpty(strResponse) Then
Dim results As New Dictionary(Of String, String)
Dim reader As New StringReader(strResponse)
Dim line As String = reader.ReadLine()
If line = "SUCCESS" Then
'FormView1.Visible = False
While True
Dim aLine As String
aLine = reader.ReadLine
If aLine IsNot Nothing Then
Dim strArr() As String
strArr = aLine.Split("=")
results.Add(strArr(0), strArr(1))
Else
Exit While
End If
End While
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'when code below is uncommented remove these two end if's below
Response.Write("<li> " + results("payer_id") + "</li>")
Response.Write("<li> " + results("txn_id") + "</li>")
' Displays all the keys for results, helps to see what the keys are named for writing to text file
For Each kvp As KeyValuePair(Of String, String) In results
Dim v1 As String = kvp.Key
Dim v2 As String = kvp.Value
Response.Write(v1.ToString _
+ ": " + v2 + "<br /> ")
Next
End If