510 - Can't access your local URL: http://localhost:port-no/Default.aspx

Dears,
i create aspx page and use pdfcrowed client object to convert my web page to PDF file as follow
// create an API client instance
pdfcrowd.Client client = new pdfcrowd.Client("usernamr", "key");
// convert a web page and write the generated PDF to a memory stream
MemoryStream Stream = new MemoryStream();
client.convertURI(currentPageUrl, Stream);
but when page loaded and click button to start convert page i got exception of pdfcrowd.Error :
510 - Can't access your local URL: http://localhost:7262/Default.aspx

please want to test my web page and i don;t know how .