How to click HTML button programatically by vb.net - vb.net

Question

I am trying to click a button programatically . The button is on the 3rd page of the website. and it does not have any id . It has just name , type and value . The HTML code of the button is given below
<FORM NAME='form1' METHOD='post' action='/dflogin.php'>
<INPUT TYPE='hidden' NAME='txtId' value='E712050-15'>
<INPUT TYPE='hidden'NAME='txtassId' value='1'>
<INPUT TYPE='hidden' NAME='txtPsw' value='HH29'>
<INPUT TYPE='hidden' NAME='txtLog' value='0'>
<h6 align='right'>
<INPUT TYPE='SUBMIT' NAME='btnSub' value='Next' style='background-color:#009900; color:#fff;'></h6></FORM>
I have tried these codes in vb.net 2008 express edition...
For Each webpageelement As HtmlElement In allelements
If webpageelement.GetAttribute("value") = "Next" Then
webpageelement.InvokeMember("click")
End If
Next
And 2nd one
theElementCollection = WebBrowser1.Document.GetElementsByTagName("INPUT")
For Each curElement As HtmlElement In theElementCollection
ctrlIdentity = curElement.GetAttribute("innerText").ToString
If ctrlIdentity = "Next" Then
curElement.InvokeMember("click")
End If
Next
and 3rd one is
Dim l_forms = WebBrowser1.Document.GetElementsByTagName("form")
If l_forms.Count > 0 Then
l_forms.Item(0).InvokeMember("submit")
End If
and 4th one is
Do While WebBrowser1.ReadyState <> WebBrowserReadyState.Complete
Application.DoEvents()
Loop
WebBrowser1.Document.Body.InnerHtml = Replace(WebBrowser1.Document.Body.InnerHtml,"NAME='btnSub'", "NAME='btnSub' id='btnSub'") 'insert id into youre button
WebBrowser1.Document.GetElementById("btnSub").InvokeMember("click") 'click on btnSub
and the last one is
Dim i As Integer
Dim allButtons As HtmlElementCollection
allButtons = WebBrowser1.Document.GetElementsByTagName("input")
i = 0
For Each webpageelement As HtmlElement In allButtons
i += 1
If i = 5 Then
webpageelement.InvokeMember("click")
End If
Next
These all codes are unable to click that button. Kindly Please Suggest a appropriate solution for clicking this button. Thank You So Much

Answer 1

something like this would be a server side JavaScript and jquery solution
string script = "$(document).ready(function() {$('input[name=btnSub]').trigger('click'); });";
ScriptManager.RegisterStartupScript(this, GetType(), "ServerControlScript", script, true);