HttpWebRequest com HTTPS

Ola amigos!

Estou tendo um problema que nao consigo resolver de forma alguma. Eu tenho um codigo que acessa uma paginae traz o conteudo dela pra mim...isso funciona normalmente com HTTP mas quando tento usar HTTPS da erro.

Segue abaixo o codigo:

Dim strURL as string = "https://www16.bb.com.br/site/mpag/"
Dim loHttp As HttpWebRequest = WebRequest.Create(strURL)
Dim lcPostData As String
Dim lbPostBuffer As Byte()
Dim loPostData As Stream

lcPostData = "idConv=" & HttpUtility.UrlEncode("0000")
lcPostData += "&valor=" & HttpUtility.UrlEncode("7850")
lcPostData += "&refTran=" & HttpUtility.UrlEncode("00000000000000000")
lcPostData += "&nome=" & HttpUtility.UrlEncode("Lucas")
lcPostData += "&endereco=" & HttpUtility.UrlEncode("AV teste, 2373- RUA 2, 79 A")
lcPostData += "&cidade=" & HttpUtility.UrlEncode("Taubaté")
lcPostData += "&estado=" & HttpUtility.UrlEncode("SP")
lcPostData += "&cep=" & HttpUtility.UrlEncode("12032000")
lcPostData += "&dtVenc=" & HttpUtility.UrlEncode("07122006")

 lcPostData += "&msgLoja=" & HttpUtility.UrlEncode("Pagamento válido somente até a data de vencimento!<br><br><br><br><br><br><br><br><b>Número do pedido:</b> 000")
 lcPostData += "&versao=" & HttpUtility.UrlEncode("02")
 lcPostData += "&moeda=" & HttpUtility.UrlEncode("986")
 lcPostData += "&convClasse=" & HttpUtility.UrlEncode("001")
 lcPostData += "&tpPagamento=" & HttpUtility.UrlEncode("2")
 lcPostData += "&urlRetorno=" & HttpUtility.UrlEncode("[http://www.sss.com.br")](http://www.sss.com.br)

 lbPostBuffer = Encoding.GetEncoding(1252).GetBytes(lcPostData)

 loHttp.Method = "POST"
 loHttp.ContentLength = lbPostBuffer.Length
 loHttp.Timeout = 1000000
 loHttp.UserAgent = Request.UserAgent.ToString

 loPostData = loHttp.GetRequestStream()
 loPostData.Write(lbPostBuffer, 0, lbPostBuffer.Length)
 loPostData.Close()

 Dim loWebResponse As HttpWebResponse = loHttp.GetResponse()

 Dim Enc As Encoding = Encoding.GetEncoding(1252)
 Dim loResponseStream As StreamReader = New StreamReader(loWebResponse.GetResponseStream(), Enc)

 lbCode.Text = loResponseStream.ReadToEnd().ToString

 loWebResponse.Close()
 loResponseStream.Close()

Erro que ele gera:

>
Server Error in '/diretorio' Application.

The remote certificate is invalid according to the validation procedure.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

a

Exception Details: System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[AuthenticationException: The remote certificate is invalid according to the validation procedure.]

System.Net.Security.SslState.StartSendAuthResetSignal(ProtocolToken message, AsyncProtocolRequest asyncRequest, Exception exception) +1036898

System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) +333

System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) +313

System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest) +386

System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) +293

System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) +297

System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) +364

System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) +313

System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest) +386

System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) +293

System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) +297

System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) +364

System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) +313

System.Net.Security.SslState.ProcessReceivedBlob(Byte[] buffer, Int32 count, AsyncProtocolRequest asyncRequest) +386

System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest) +293

System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest) +297

System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest) +364

System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest) +313

System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest) +138

System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult) +120

System.Net.TlsStream.CallProcessAuthentication(Object state) +47

System.Threading.ExecutionContext.runTryCode(Object userData) +66

System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(

ryCode code, CleanupCode backoutCode, Object userData) +0

System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) +166

System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) +145

System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result) +728

System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size) +44

System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size) +21

System.Net.ConnectStream.WriteHeaders(Boolean async) +266

[WebException: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.]

System.Net.HttpWebRequest.GetRequestStream() +1504461

aaa.grabber.urlGrabber(String strURL) in ---grabber.aspx.vb:64

aaa.grabber.Page_Load(Object sender, EventArgs e) in ---grabber.aspx.vb:31

System.Web.UI.Control.OnLoad(EventArgs e) +99

System.Web.UI.Control.LoadRecursive() +47

System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1061

Version Information: Microsoft .NET Framework Version:2.0.50727.42; ASP.NET Version:2.0.50727.210

using System.Net.Security;
using System.Security.Cryptography.X509Certificates;

	bool validationResult = true;
	return validationResult;
};