VB.NET POST 返回值获取失败

[LittleCalabash]

Imports System
Imports System.IO
Imports System.Net
Imports System.Text
Imports System.Web
Imports System.Web.Security.FormsAuthentication

Dim Web As New System.Net.WebClient()
Web.Headers.Add("Content-Type", "application/x-www-form-urlencoded")
Dim uid As String = TextBox1.Text
Dim pwd As String = TextBox2.Text
Dim paraCode As String = "{" + """" + "username" + """" + ":" + """" + uid + """" + "," + """" + "password" + """" + ":" + """" + pwd + """" + "}"
Dim AR As Byte() = System.Text.Encoding.GetEncoding(-0).GetBytes(paraCode)
Dim Str As Byte() = Web.UploadData("http://180.169.1.222:8082/api/login?para=", "POST", AR)
LinkLabel1.Text = "http://180.169.1.222:8082/api/login?para="
LinkLabel2.Text = paraCode
LinkLabel3.Text = "Url + " + Convert.ToBase64String(AR)
RichTextBox1.Text = "Address:" & Chr(10) & "http://180.169.1.222:8082/api/login?para=" + Convert.ToBase64String(AR) & Chr(10) & System.Text.Encoding.ASCII.GetString(Str)

最后生成出的链接直接在公司的调试软件里可以连接成功，有返回值，如下：


{
"result": "SUCCESS",
"data": "eyJpZCI6InhzYyIsInVzZXJuYW1lIjoieHNjIiwicGFzc3dvcmQiOiJiZDAwMTU2MzA4NWZjMzUxNjUzMjllYTFmZjVjNWVjYmRiYmVlZiIsImZ1bGxuYW1lIjoi5paw6KeG56qXIiwicm9sZWlkIjoyLCJkZXB0aWQiOjMsInJlZ2lzdF90aW1lIjoxNDk0MjE2MDY1MDAwLCJ0eXBlIjowLCJka2V5IjoiYTE4OGZkYWEtZTMyOC00NWM1LWIzMjUtNDJkMDg5ODNkMTQ3IiwiZGVwdF9uYW1lIjoi5paw6KeG56qXIiwidHAiOiJUT1BJQ18zIn0=",
"errorCode": 0
}

但是在VB.NET里无论如何都显示获取结果失败 {"result":"FAILED","errorCode":0}
如下图：

跪求大仙们帮帮我吧，我头都要炸了，水平有限到现在我都没找到原因所在。。。