XML parsing error: XML or text declaration not at start of entity

edit

I keep getting this error on my xacro file. To be honest I am not familiar with this kind of format and I was wondering if I could get any help for the bad syntax error that keeps popping. Thanks in advance

<?xml version="1.0"?>
<!--
  The complete turtlebot library of xacros for easy reference
 -->
<robot xmlns:xacro="http://ros.org/wiki/xacro">
  <!-- General -->
  <xacro:include filename="$(find turtlebot_description)/urdf/common_properties.urdf.xacro"/>
  <xacro:include filename="$(find turtlebot_description)/urdf/turtlebot_properties.urdf.xacro"/>
  <!-- Bases -->
  <xacro:include filename="$(find create_description)/urdf/create.urdf.xacro"/>
  <xacro:include filename="$(find kobuki_description)/urdf/kobuki.urdf.xacro" />
  <!-- Stacks -->
  <xacro:include filename="$(find turtlebot_description)/urdf/stacks/circles.urdf.xacro"/>
  <xacro:include filename="$(find turtlebot_description)/urdf/stacks/hexagons.urdf.xacro"/>
  <!-- 3D Sensors -->
  <xacro:include filename="$(find turtlebot_description)/urdf/sensors/kinect.urdf.xacro"/>
  <xacro:include filename="$(find turtlebot_description)/urdf/sensors/asus_xtion_pro.urdf.xacro"/>
  <xacro:include filename="$(find turtlebot_description)/urdf/sensors/asus_xtion_pro_offset.urdf.xacro"/>
  <xacro:include filename="$(find turtlebot_description)/urdf/sensors/astra.urdf.xacro"/>
  <xacro:include filename="$(find turtlebot_description)/urdf/sensors/r200.urdf.xacro"/>
  <!-- 2D Sensors -->  
  <xacro:include filename="$(find turtlebot_description)/urdf/sensors/hokuyo.urdf.xacro"/>
</robot>