POST request created in vba brings back nothing as result - vba

Question

I've written a very tiny script in vba using POST request. However, when I run it, I get nothing as result except for a blank message. I've tried to fill in the request parameter accordingly. Perhaps, I can't notice which should be included in the parameter. The page I'm dealing with contains several images in it's right panel. When an image is clicked the request about which i'm talking here is sent to the server and brings back the result and displays new information concerning its' flavor under it. My goal is to parse all the flavors connected to each images. Anyways, I'm trying to attach all the things necessary to find out what i'm missing. Thanks in advance.
This is what I got from chrome developer tools to prepare the POST request:
"https://www.dropbox.com/s/zjn0ahixhu58miq/RequestStatus.txt?dl=0"
Here is what I'm trying with:
Sub PostReq()
Dim http As New XMLHTTP60, html As New HTMLDocument
Dim ArgumentStr As String
ArgumentStr = "opt=flavor&opt1=207&opt2=47&ip=105"
With http
.Open "POST", "https://www.optigura.com/product/ajax/details.php", False
.setRequestHeader "User-Agent", "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36"
.setRequestHeader "Content-type", "application/x-www-form-urlencoded"
.setRequestHeader "Accept", "application/json, text/javascript, */*; q=0.01"
.send ArgumentStr
html.body.innerHTML = .responseText
End With
MsgBox http.responseText
End Sub
This is the original link to the webpage:
"https://www.optigura.com/uk/product/gold-standard-100-whey/"

Answer 1

Your code sets a request header like so:
.setRequestHeader "Content-type", "application/x-www-form-urlencoded"
so the script is going to expect the argument string to be URL encoded (which it isn't).
Try either encoding the string, or send the request using "GET" instead.

Answer 2

Finally, I've made it. To receive the required response it is necessary to send a GET request first then again send a POST request using the response from that get request. Here is the working one:
Sub httpPost()
Dim http As New XMLHTTP60, html As New HTMLDocument
Dim ArgumentStr As String
ArgumentStr = "opt=flavor&opt1=207&opt2=47&ip=105"
With http
.Open "GET", "https://www.optigura.com/uk/product/gold-standard-100-whey/", False
.send
End With
With http
.Open "POST", "https://www.optigura.com/product/ajax/details.php", False
.setRequestHeader "X-Requested-With", "XMLHttpRequest"
.setRequestHeader "Content-type", "application/x-www-form-urlencoded"
.setRequestHeader "Accept", "application/json, text/javascript, */*; q=0.01"
.send ArgumentStr
html.body.innerHTML = .responseText
End With
MsgBox http.responseText
End Sub