catkin can't find python service files

edit

I've got a python node which runs a service server. Catkin builds it fine and builds the service files (works fine for another package in C++ which uses the same .srv file). Even though it builds the file fine, at runtime the node can't import it. If I revise the python search path as shown:

PYTHONPATH='/home/blake/Projects/Ros/catkin_ws/devel/lib/python2.7/dist-packages/retractor_ros/srv/':$PYTHONPATH

it works. Here's my CMakelist.txt

cmake_minimum_required(VERSION 2.8.3)
project(retractor_ros)

set(BH_LIB_NAME XXXXXXXXXXX)


## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRE COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTS
  rospy
  roscpp
  std_msgs
  message_generation
  ${BH_LIB_NAME}
)


## Generate services in the 'srv' folder
add_service_files(
   FILES
   PhidgetsServoCommand.srv
#   Service1.srv
#   Service2.srv
)

## Generate added messages and services with any dependencies listed here
 generate_messages(
   DEPENDENCIES
   std_msgs
 )

catkin_package(
  INCLUDE_DIRS 
#   LIBRARIES ${BH_LIB_NAME}
  CATKIN_DEPENDS message_runtime rospy roscpp std_msgs rstate_machine
#  DEPENDS system_lib
)

###########
## Build ##
########### 
include_directories(
  ${catkin_INCLUDE_DIRS}
#   /opt/ros/hydro/include/turtle_actionlib
  /home/blake/Projects/Ros/catkin_ws/devel/include/retractor_ros
  /home/blake/Projects/Ros/catkin_ws/src/pwm_ros
  /home/blake/Projects/Ros/catkin_ws/src/rstate_machine/include
)


## Declare a cpp executable
add_executable(retractor_ros_node retractor_fsm.cpp keyinput.cpp)
target_link_libraries(retractor_ros_node ${BH_LIB_NAME} ${catkin_LIBRARIES})

add_dependencies(${PROJECT_NAME}_node servo_fsm_generate_messages_cpp keyinput.cpp rstate_machine.cpp)

install(PROGRAMS
   scripts/pwm_servo.py
   ../devel/lib/retractor_ros/retractor_ros_node
   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
   )

## Mark executables and/or libraries for installation
install(TARGETS retractor_ros_node
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
 )