How to use custom defined messages in another package?

edit

I am new to ros and was writing code to publish and listen to a custom message. I am running ROS kinetic on Debian machine.

In my workspace I have two package - aa and bb. aa has a message two_ints as follows:

int16 a1
int16 b1

Both the packages use this message. When I catkin_make my workspace I get the following error in source of bb:

.../catkin_new/src/bb/src/src_bb.cpp:2:24: fatal error: aa/two_ints.h: No such file or directory

The CMakeLists.txt of aa is

cmake_minimum_required(VERSION 2.8.3)
project(aa)
find_package(catkin REQUIRED COMPONENTS
  roscpp
  std_msgs
  message_generation
)
add_message_files(
   FILES
   two_ints.msg
)
 generate_messages(
   DEPENDENCIES
   std_msgs
)
catkin_package(
  INCLUDE_DIRS include
  LIBRARIES aa
  CATKIN_DEPENDS roscpp std_msgs message_runtime
)
include_directories(
  ${catkin_INCLUDE_DIRS}
)
add_executable(talker src/src_aa.cpp)
target_link_libraries(talker ${catkin_LIBRARIES})
add_dependencies(talker aa_generate_messages_cpp)

And CMakeLists.txt of bb is

cmake_minimum_required(VERSION 2.8.3)
project(bb)
find_package(catkin REQUIRED COMPONENTS
  roscpp
  std_msgs
)
catkin_package(
  INCLUDE_DIRS include
  LIBRARIES bb
  CATKIN_DEPENDS roscpp std_msgs
)
include_directories(
  ${catkin_INCLUDE_DIRS}
)
add_executable(listener src/src_aa.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
add_dependencies(listener aa_generate_messages_cpp)

Directory structure is:

catkin_new
  -build
  -devel
  -src
     -CMakeLists.txt
     -aa
        -msg
           -two_ints.msg
        -include
        -src
           src_aa.cpp
        -...
     -bb
        -CMakeLists.txt
        -src
           -src_bb.cpp
        -...

Please help me out. I have tried various things but in vain. Also talker gets built even though it also includes aa/two_ints.h. Why so? And two_ints.h is present in devel/aa/ directory.

EDIT: The aa/package.xml is:

<?xml version="1.0"?>
<package>
  <name>aa</name>
  <version>0.0.0</version>
  <description>The aa package</description>
  <license>TODO</license>
  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_depend>message_generation</build_depend>
  <run_depend>roscpp</run_depend>
  <run_depend>std_msgs</run_depend>
  <run_depend>message_runtime</run_depend>
  </package>

The `bb/CMakeLists.txt' is modified and is as follows:

cmake_minimum_required(VERSION 2.8.3)
project(bb)
find_package(catkin REQUIRED COMPONENTS
  roscpp
  std_msgs
  aa #changed here
)
catkin_package(
  INCLUDE_DIRS include
  LIBRARIES bb
  CATKIN_DEPENDS roscpp std_msgs aa #changed here
)
include_directories(
  ${catkin_INCLUDE_DIRS}
)
add_executable(listener src/src_aa.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
add_dependencies(listener aa_generate_messages_cpp)

The 'bb/package.xml' is:

<package>
  <name>bb</name>
  <version>0.0.0</version>
  <description>The bb package</description>
  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_depend>aa</build_depend>
  <run_depend>roscpp</run_depend>
  <run_depend>std_msgs</run_depend>
  <run_depend>aa</run_depend>
</package>

Now when I catkin_make the catkin_new workspace I get following error:

CMake Error at /home/mayank/Workspace/catkin_new/devel/share/aa/cmake/aaConfig.cmake:141 (message):
  Project 'bb' tried to find library 'aa'.  The library is neither a target
  nor built/installed properly.  Did you compile project 'aa'? Did you
  find_package() it before the subdirectory containing its code is included?
Call Stack (most recent call first):
  /opt/ros/kinetic/share/catkin/cmake/catkinConfig.cmake:76 (find_package)
  bb/CMakeLists.txt:10 (find_package)

Looks like bb is getting built before/in parallel with aa. What am I missing?