libFLAC_static / CMake

  Hello,

trying to compile a project with MSVC++ and libFLAC_static.lib I have a 
CMakeLists.txt with this:

set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} libFLAC_static.lib)
optional(HAVE_FLAC FLAC/all.h libFLAC_static FLAC__stream_encoder_new flac)
optional(STATIC_FLAC FLAC/all.h libFLAC_static FLAC__stream_encoder_new 
flac)

CMake answer (the *.lib is always found):
Looking for FLAC__stream_encoder_new in libFLAC_static - not found

If I put "libFLAC.lib" instead of "libFLAC_static.lib" it is found. Any 
idea?

Thanks a lot!
Regards
Thomas