FlashRunTimeExtensions error

Hello. I don't know exactly where to post this because it is not specific to any Adobe software

I have to build some project in C++ which uses FlashRunTimeExtensions.lib functions to interface with Unity.

The first thing is I have to build for x64 architectures. So I build with Visual Studio in Release x64.

I get the following message from the linker:

error LNK2019: unresolved external symbol xxxx referenced in function xxxx. This 16 times. All this symbols are provided by the FRTE.lib.

It seems I build with the good options to include this library because it worked in 32 bits and I use almost the same options with 64 bits(same include and lib paths).

I wonder if it is due to differences with 32/64 bits(this lib is maybe not builded in 64 bits) or if I'm getting wrong in the project configuration.

Thanks in advance for all your answers