http client cannot access secured web service

[groads2]

My application uses httpwebrequest class to access a secured service. I have received a certificate which I installed on the pc. the web service requires a username and password. I get the following message when running the app:

"The underlying connection was closed. Could not establish trust relationship for the SSL/TLS secure channel"

 

My code is below but I don't know what is wrong or what else to do. Thanks.

 

Dim cert As System.Security.Cryptography.X509Certificates.X509Certificate

cert = System.Security.Cryptography.X509Certificates.X509Certificate.CreateFromCertFile("c:\was33.cer")

 

Dim defaultUri As String = String.Empty

defaultUri = "https://111.111.11.11:999/services/queryservice"

Dim query As String = String.Empty

Dim urii As String = String.Empty

Dim postData As String = String.Empty

 

 

Dim responseData As String = String.Empty

Dim hwrequest As System.Net.HttpWebRequest

 

urii = defaultUri

 

hwrequest = System.Net.HttpWebRequest.Create(urii)

hwrequest.Method = "POST"

hwrequest.Accept = "gzip, deflate"

hwrequest.ContentType = "text/xml; charset=utf-8"

hwrequest.Timeout = 20000

 

hwrequest.Credentials = New System.Net.NetworkCredential("psc8", "psw8")

 

hwrequest.ClientCertificates.Add(cert)

 

If Not String.IsNullOrEmpty(txtQuery.Text) Then

postData = txtQuery.Text

End If

 

Dim encoding As New Text.ASCIIEncoding() 'Use UTF8Encoding for XML requests

Dim postByteArray() As Byte = encoding.GetBytes(postData)

 

hwrequest.ContentLength = postByteArray.Length

Try

Dim postStream As IO.Stream = hwrequest.GetRequestStream()

postStream.Write(postByteArray, 0, postByteArray.Length)

postStream.Close()

Catch ex As Exception

txtReply.Text = ex.Message

Exit Sub

End Try

 

Dim hwresponse As Net.HttpWebResponse = hwrequest.GetResponse()

Try

 

If hwresponse.StatusCode = Net.HttpStatusCode.OK Then

Dim responseStream As IO.StreamReader = _

New IO.StreamReader(hwresponse.GetResponseStream())

responseData = responseStream.ReadToEnd()

End If

 

Catch ex As Exception

responseData = ex.Message.ToString

End Try

hwresponse.Close()