CMake Error #22

报错：
CMake Error at plumbing_server_client/CMakeLists.txt:136 (add_executable):
Cannot find source file:

src/demo01_server.cpp

Tried extensions .c .C .c++ .cc .cpp .cxx .cu .m .M .mm .h .hh .h++ .hm
.hpp .hxx .in .txx

CMake Error at plumbing_server_client/CMakeLists.txt:136 (add_executable):
No SOURCES given to target: demo01_server
CMakelist配置：
add_executable(demo01_server src/demo01_server.cpp)

add_dependencies(demo01_server ${PROJECT_NAME}_gencpp)

target_link_libraries(demo01_server
${catkin_LIBRARIES}
)

ps：确认demo01_server.cpp在src下且未拼错名字