Add reference failing C#

I have a wcf service running and I was trying to implement a tcp model on it so I made a windows service and tried adding the WCF service as a reference to it which worked fine. But when i tried to build the windows service it gave me an error as "The type or namespace name '*' could not be found (are you missing a using directive or an assembly reference?)". In fact I tried 开发者_运维百科to add my dal project as reference and the same error cropped up. I implemented a POC just to check if I am doing things correctly which worked fine. But it fails on my solution am I missing some configuration thing I am confused please help thanks.

It is important that you document the type name that it complains about to get a good answer. Avoid targeting the .NET client profile whenever you do something webby. System.Web.dll is not part of it.

Project + Properties, Application tab, Target framework combo.

Thank's for all the help guys I got the reason why it was failing all my other projects are having target framework as .Net Framework 4. But each time I add a new project to my solution they are been targeted to .Net Framework 4 Client Profile. Which I changed and everything worked fine. Thank's again for the help.