When working with web.config, Configuration class is not available

I want to access the "appSettings" section of a web.config file. According to MSDN and multiple other sources, the following should work:

System.Configuration.Configuration config = 
    WebConfigurationManager.OpenWebConfiguration("/rootPath");

I received this error on the second configuration (System.Configuration.Configuration):

The type or namespace name 'Configuration' does not exist in the namespace 'System.Configuration'(are you missing an assembly reference?)

I received an additional error on system (System.Configuration.Configuration):

The type 'System.Configuration.Configuration' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Configuration, Version=2.0.0.0, Culture=Neutral, PublicKeyToken=b03f5f7f11d50a3a'.

Addressing the first error, I have a reference to System.Configuration. When I look 开发者_开发问答in Object Browser, it contains a class definition for Configuration.

Addressing the second error, the reference is for version 2.0.50727. Is there a version 2.0.0.0?

The second error popped up after I deleted, and re-added the reference to System.Configuration. Also, after re-adding the reference it now displays as "System.configuration" in my references. Note the lowercase c.

Additional Notes

Things I've tried and failed:

• Deleted and added the reference to System.Configuration
• Deleted all references for the project and added them back
• Checked out a clean solution from SVN

I created a test solution and had no problems accessing the class in the System.Configuration namespace.

Any ideas on what is going on (how did I eff this up)? What avenues can I try to fix it?

This is so stupid, I want to delete this question and quietly back away. Perhaps it'll be useful to some other fool. Eilon was on the right track, I was adding the reference to the wrong project.

I was in a time crunch trying to get a project production ready and was not very focused (trying to do several things at once). Ah well, I'm still new to this and hopefully next time I will take a deep breath and not stress out...and start the project out with connection strings stored in the web config.

Try to remove that references to System.Configuration and do it from scratch: you should to add version=2.0.0.0 (for runtime version v2.0.50727). Then, to read your appSetting, you could just write this:

string value = System.Configuration.ConfigurationManager.AppSettings["yourKey"];