Creating new tasks with the Wrike API and VB.net - vb.net

Question

I'm having trouble creating new Wrike tasks using VB.net and the Wrike API. I however, am able to connect to Wrike to GET a list of folders so I know I'm able to successfully authenticate.
Link to task creation docs:
https://developers.wrike.com/documentation/api/methods/create-task
The only required field is "Title"
Dim accessToken As String = API_Token
Dim apiVersion As String = "v4"
Dim ApiBaseUrl As String = "https://www.wrike.com"
Dim folderID As String = "Some Folder ID Here"
Dim address As String = ApiBaseUrl & "/api/" & apiVersion & "/folders/" & folderID & "/tasks"
Dim result As String
Dim task_str_ As String = "importance=Normal&description=Test task description&dates={""start"":""2019-07-24"",""due"":""2019-07-30""}&title=Task Created With VS&status=Active"
Try
Dim request As HttpWebRequest = TryCast(WebRequest.Create(address), HttpWebRequest)
request.Headers.Add("Authorization", "Bearer " & accessToken)
request.Method = "PUT"
request.ContentType = "application/json"
Using requestWriter2 As New StreamWriter(request.GetRequestStream())
requestWriter2.Write(task_str_)
End Using
Dim webResp As WebResponse = request.GetResponse()
Using reader = New StreamReader(webResp.GetResponseStream)
result = reader.ReadToEnd()
End Using
TextBox1.Text = (result)
Catch ex As Exception
TextBox1.Text = ex.ToString
End Try
Here is the error I'm receiving:
System.Net.WebException: The remote server returned an error: (400) Bad Request

Answer 1

Once I made the suggested changes, everything works good.
Dim accessToken As String = API_Token
Dim apiVersion As String = "v4"
Dim ApiBaseUrl As String = "https://www.wrike.com"
Dim folderID As String = "Some Folder ID Here"
Dim address As String = ApiBaseUrl & "/api/" & apiVersion & "/folders/" & folderID & "/tasks"
Dim result As String
Dim task_str_ As String = "importance=Normal&description=Test task description&dates={""start"":""2019-07-24"",""due"":""2019-07-30""}&title=Task Created With VS&status=Active"
Try
Dim request As HttpWebRequest = TryCast(WebRequest.Create(address), HttpWebRequest)
request.Headers.Add("Authorization", "Bearer " & accessToken)
request.Method = "POST"
request.ContentLength = task_str_.Length
request.ContentType = "application/x-www-form-urlencoded"
Using requestWriter2 As New StreamWriter(request.GetRequestStream())
requestWriter2.Write(task_str_)
End Using
Dim webResp As WebResponse = request.GetResponse()
Using reader = New StreamReader(webResp.GetResponseStream)
result = reader.ReadToEnd()
End Using
TextBox1.Text = (result)
Catch ex As Exception
TextBox1.Text = ex.ToString
End Try