add_custom_command not working - cmake

Question

I am trying to understand add_custom_command usage, I wrote a minimal make file (CMakeLists.txt)
like shown below
When I run the make file using
$cmake.
$make
I don't see perfecthash.cpp being created and the build breaks
cmake_minimum_required(VERSION 2.8)
# Call add_custom_command() with appropriate arguments for generate output file
# Note, that *gperf* will work in the build tree,
# so for file in the source tree full path should be used.
function(gperf_generate_new input output)
MESSAGE("debugging function")
add_custom_command(
OUTPUT ${output}
COMMAND gperf -L c++ ${input} > ${output}
DEPENDS ${input}
COMMENT "printing ${output}" # Just for nice message during build
)
endfunction()
# Generate *example.hpp* file ...
gperf_generate_new(command_options.new.gperf pefecthash.hpp)
# ... for use it in executable
add_custom_target(my_target
ALL # Force target to be built with default build target.
DEPENDS perfecthash.hpp
)
$cmake .
$make
give the below error
-- The C compiler identification is GNU 4.9.2
-- The CXX compiler identification is GNU 4.9.2
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
debugging function
-- Configuring done
-- Generating done
-- Build files have been written to: /home/srinivas
Scanning dependencies of target my_target
make[2]: *** No rule to make target `perfecthash.hpp', needed by `CMakeFiles/my_target'. Stop.
make[1]: *** [CMakeFiles/my_target.dir/all] Error 2
make: *** [all] Error 2

Answer 1

Just a typo:
gperf_generate_new(command_options.new.gperf pefecthash.hpp)
...
DEPENDS perfecthash.hpp