When POSTing and receiving response: "End of file reached in invalid state for current encoding" error

Hi!
I have a problem with my page, when getting the response from a request to another server, sometimes it works, and sometimes it doesn't..  
Roughly my function looks like:
Dim myCall As New MSXML2.ServerXMLHTTP60
Dim data As String = "somestring"
myCall.open("POST", "https://myHTTPSpage/", False)
myCall.setRequestHeader("Content-type","application/x-www-form-urlencoded") 
myCall.setRequestHeader("Content-Length", (data.Length).ToString)
myCall.setRequestHeader("X-NP-Version", "2.1")
myCall.send(data)
 
If (myCall.responseText.Length = 0) Then
    Response.Write("No response text") 
Else
    - print response
End If 


And I get the " ...