Malformed Request when sending postdata(VB.net)

I am trying to complete Timed2 using vb.net. I have completed the part where it adds up the numbers, but now I am having problems with postdata. When I use the following code it results in a malformed request:

Dim postdata As String = "ans=test"

    Dim a As System.Text.Encoding = System.Text.Encoding.UTF8

    Dim byte1 As Byte() = a.GetBytes(postdata)

    Dim AdditionalHeaders As String = "Content-Type: application/x-www-form-urlencoded" + Environment.NewLine

    WebBrowser1.Navigate("http://www.hellboundhackers.org/challenges/timed/timed2/index.php?check", "", byte1, AdditionalHeaders)

What can I do to make it work?

Send a referer header ;)

Thank you:) A little stupid of me not figuring it out myself, I just realised that it said that I should check for referer spoofers at the bottom of the page. :angry: