message header doesn't build

edit

I know this question has been asked a number of times, and I've gone through and followed the instructions on a number of those answers (for example- here and here), as well as in the documentation for building a custom message. Yet still my message header is not building.

This is the error I get:

/home/erinline/Documents/testsim/src/m-explore/explore/src/explore.cpp:39:10: fatal error: msg/util.h: No such file or directory


#include <msg/util.h>
          ^~~~~~~~~~~~
compilation terminated.
m-explore/explore/CMakeFiles/explore.dir/build.make:86: recipe for target 'm-explore/explore/CMakeFiles/explore.dir/src/explore.cpp.o' failed
make[2]: *** [m-explore/explore/CMakeFiles/explore.dir/src/explore.cpp.o] Error 1
CMakeFiles/Makefile2:23711: recipe for target 'm-explore/explore/CMakeFiles/explore.dir/all' failed
make[1]: *** [m-explore/explore/CMakeFiles/explore.dir/all] Error 2
Makefile:140: recipe for target 'all' failed
make: *** [all] Error 2
Invoking "make -j4 -l4" failed

This is my CMakeLists.txt:

cmake_minimum_required(VERSION 2.8.3)
project(explore_lite)

## Find catkin macros and libraries
find_package(catkin REQUIRED COMPONENTS
  actionlib
  actionlib_msgs
  costmap_2d
  geometry_msgs
  map_msgs
  move_base_msgs
  nav_msgs
  roscpp
  std_msgs
  tf
  visualization_msgs
  message_generation
)

add_message_files(
  FILES
  util.msg
)

generate_messages(
  DEPENDENCIES
  std_msgs
)

###################################
## catkin specific configuration ##
###################################
catkin_package(
  CATKIN_DEPENDS
    actionlib_msgs
    geometry_msgs
    map_msgs
    move_base_msgs
    nav_msgs
    std_msgs
    visualization_msgs
    message_runtime
)

###########
## Build ##
###########
# c++11 support required
include(CheckCXXCompilerFlag)
check_cxx_compiler_flag("-std=c++11" COMPILER_SUPPORTS_CXX11)
if(COMPILER_SUPPORTS_CXX11)
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
else()
  message(FATAL_ERROR "The compiler ${CMAKE_CXX_COMPILER} has no C++11 support. Please use a different C++ compiler.")
endif()

## Specify additional locations of header files
include_directories(
  ${catkin_INCLUDE_DIRS}
  include
)

add_executable(explore
  src/costmap_client.cpp
  src/explore.cpp
  src/frontier_search.cpp
)
#add_dependencies(explore ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

add_dependencies(explore explore_lite_generate_messages_cpp)
target_link_libraries(explore ${catkin_LIBRARIES})

#############
## Install ##
#############

# install nodes
install(TARGETS explore
  ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
  LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
  RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)

# install roslaunch files
install(DIRECTORY launch/
  DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}/launch
)

#############
## Testing ##
#############
if(CATKIN_ENABLE_TESTING)
  find_package(roslaunch REQUIRED)

  # test all launch files
  roslaunch_add_file_check(launch)
endif()

My message is called util.msg, it is in a file called msg within the package file called explore. I must be missing something, since those previous answers seem to work for some folks. Any advice on where I am going wrong would be greatly appreciated!