c# - HttpUtility does not exist in the current context

Question

I get this error when compiling a C# application. Looks like a trivial error, but I can't get around it.

My setup is Windows 7 64 bit. Visual-Studio 2010 C# express B2Rel.

I added a reference to System.Web.dll located at C:Program Files (x86)Reference AssembliesMicrosoftFramework.NETFrameworkv4.0, but it has a yellow exclamation symbol and I still get the above error. I also have the using System.Web declaration.

What am I doing wrong?

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Update: After getting the prompt answer pointing me at the root cause, I searched a bit in Google to where it states that System.Web.dll is for the full framework. I did not find such a reference.
For newbies like me, this blog summarizes the difference between the frameworks (client and full) nicely. I could not find a spot that says whether a certain Dll is supported in the client framework or not. I guess the exclamation mark in Visual Studio should be the first signal...

Answer 1

You need to add the System.Web reference;

1. Right click the "Reference" in the Solution Explorer
2. Choose "Add Reference"
3. Check the ".NET" tab is selected.
4. Search for, and add "System.Web".