The URI prefix is not recognized SL3 VS2010

i keep getting no matter place file.

private void client_openreadcompleted(object sender, openreadcompletedeventargs e)
		{
			system.io.streamreader sr = new system.io.streamreader(e.result);
			string s = sr.readtoend();
			sr.close();
		}

		private void usercontrol_loaded(object sender, routedeventargs e)
		{
			client.openreadcompleted += new openreadcompletedeventhandler(client_openreadcompleted);
			client.openreadasync(new uri("messages.txt", urikind.relative));
		}

looking read messages.txt. placed in bin/debug/ same error. also  told compile resource; wrong?

i new silverlight , seems file io isnt simple win32/64.

what did let generate? sample page? said, not enough; need host silverlight application in web application project.

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