No Cookies at second Webrequest

I login to a website by HTTPwebrequest, I get an authentication cookie.

When I make a new HTTP-webrequest and add the cookies from the first request to call the next page where I can see my personal data. I see that the cookies will associated with the second request if I debug it but if I check the network traffic I see that are no Cookies transmitted at the second re开发者_如何学Cquest. I tried many possibilities to see why I don't work but I found nothing.

Does anyone know a solution?