I want to learn web designing. We do not have any chapters or articles about front end design. Please suggest me some link from where i can learn this.

Try searching in your web .config file. Otherwise if possible please post the web .config file here. So that I can have a look

Please elaborate the question if possible please show the client code and how you are trying to connect

The question is bit unclear. Can you please elaborate.

Though I am not very sure, but we had a similar problem in our project. If we choose the framewrok to 4.0 (the project was supposed to run in 3.5), we used to get these errors. To resolve it go to your web.config file and change the 4.0.0.0 to 2.0.0.0. It worked for us! Hope it helps :)