The type 'System.Data.Common.DbConnection' is defined in an assembly that is not referenced

I am trying to use a SQLite database with my Windows store app I am creating.

Below is a data class that is initialized when the app starts:

public class DataLayer
{
   SQLiteConnection m_dbConnection;
   public DataLayer()
    {
        createDatabase();
    }

   public void createDatabase()
   {
       SQLiteConnection.CreateFile("QTabs.sqlite");
       m_dbConnection = new SQLiteConnection("Data Source=QTabs.sqlite;Version=3;");
       m_dbConnection.Open();
       StringBuilder creatTables = new StringBuilder();
       //Append all SQL tables
       creatTables.Append("CREATE TABLE SyncTime (SyncTime_ID INTEGER PRIMARY KEY AUTOINCREMENT, SyncTime DATETIME);");
       SQLiteCommand command = new SQLiteCommand(creatTables.ToString(), m_dbConnection);
       command.ExecuteNonQuery();
       m_dbConnection.Close();
   }
}

All I'm trying to do is have a database created and filled with a table.

But I'm getting this error:

"Error 1 The type 'System.Data.Common.DbConnection' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. C:\Users\tunnelld\Documents\Visual Studio 2013\Projects\QTabs 0.1 sqlite retry\QTabs\DataLayer.cs 14 25 QTabs"

I'm using System.Data:

using System.Data;
using System.Data.SQLite;

What is going on here? How do I fix this?

Edit: I don't see any references to add.