Linking Error of FBX SDK on CMake

Question

I encountered an error when I am trying to link the Fbx static library (libfbxsdk.a) to a project on Linux using CMake that keeps reporting for undefined references to fbx-related functions. I checked the configuration in the CMakelist and everything looks alright, but the program cannot be compiled statically or dynamically. I really don't have any idea why the static library is not linked properly and appreciate any helps to fix the linking issue. Here is my cmakelist file for static linking:

cmake_minimum_required(VERSION 3.6)
SET(CMAKE_VERBOSE_MAKEFILE ON)
project(FBX_SDK)

add_definitions(-DFBXSDK_NEW_API)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -lm -lrt -luuid -lstdc++ -lpthread -ldl -lX11 -std=c++11")

include_directories(${X11_LIBRARIES}
        ${FBX_SDK_SOURCE_DIR}/fbxsdk-1.2/include/)

link_directories(${X11_LIBRARIES}
        ${FBX_SDK_SOURCE_DIR}/fbxsdk-1.2/Lib/Linux/Debug_x64/)

set(SOURCE_FILES main.cpp)    
add_executable(FBX_SDK ${SOURCE_FILES})

target_link_libraries(FBX_SDK
        ${FBX_SDK_SOURCE_DIR}/fbxsdk-1.2/Lib/Linux/Debug_x64/libfbxsdk.a)

and my cpp file is as below:

#include <iostream>
#include <fbxsdk.h>

void InitializeSDKObjects(FbxManager* &pManager, FbxScene* &pScene);

int main() 
{
std::cout << "Hello, World!" << std::endl;

FbxManager* lSdkManager = NULL;
FbxScene* lScene = NULL;
bool lResult;

InitializeSDKObjects(lSdkManager, lScene);


return 0;
}

void InitializeSDKObjects(FbxManager* &pManager, FbxScene* &pScene)
{
pManager = FbxManager::Create();
if(!pManager)
{
    FBXSDK_printf("Error: Unable to create FBX Manager!\n");
    exit(1);
}

else FBXSDK_printf("Autodesk FBX SDK version %s\n", pManager->GetVersion());

FbxIOSettings* ios = FbxIOSettings::Create(pManager, IOSROOT);
pManager->SetIOSettings(ios);

FbxString lPath = FbxGetApplicationDirectory();
pManager->LoadPluginsDirectory(lPath.Buffer());

pScene = FbxScene::Create(pManager, "My Scene");
if(!pScene)
{
    FBXSDK_printf("Error: Unable to create FBX scene!\n");
    exit(1);
}

}

While the include and lib folders of fbx sdk are like this: