[SOLVED] Texture2D problem

For some unusual reason MonoGame 3.5 is giving me the following error that I can’t figure out. The class that is causing the problem is this:

using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

namespace PC_ScreenManager
public class PCScreenManager
protected struct GameScreen
private Texture2D _Background;
private string _Name;
private int _Index;

		public _Texture2D_ Background

		** This of course is not the entire class, just the area in question.

This generates the following error: CS0246 The type or namespace name ‘Texture2D’ could not be found (are you missing a using directive or an assembly reference?)

This is in VS 2015, MonoGame 3.5. The file was originally designed in VS 2010 with XNA 4.0 and was made into the new project via the new project from
existing code menu option due to the fact that VS14 will not import a VS9 project. Help?

Solved the problem; I was trying to build the .dll from inside a game type project. Duh!