I am using ASP.NET(VB) to call API

Try
            Dim strUrl As String = "https://blockchain.info/tobtc?currency=USD&value=500"
            Dim request As WebRequest = HttpWebRequest.Create(strUrl)
            Dim response As HttpWebResponse = DirectCast(request.GetResponse, HttpWebResponse)
            Dim s As Stream = DirectCast(response.GetResponseStream(), Stream)
            Dim readStream As New StreamReader(s)
            Dim dataString As String = readStream.ReadToEnd()
            response.Close()
            s.Close()
            readStream.Close()
            Return dataString
        Catch ex As Exception
            Return "N"
        End Try

It's working fine. But when I am using API for Getting Balance

Dim strUrl As String = "https://blockchain.info/merchant/<<GUID>>/address_balance?password=<<PASSWORD>>&address=<<BTC_ADDRESS>>

It's getting Error 404 Not Found. In the example on Blockchain website its showing "http://localhost:3000/" How can it same for everyone.