为ARM mbed编译PicoTCP时，未定义对pico_dhcp_server_initiate的引用

我正在进行一个必须使用PicoTCP的项目(请参阅https://developer.mbed.org/users/daniele/code/PicoTCP/，我使用的是这个库的旧版本(。在我的main.cpp文件中，我有以下代码：

#include "pico_stack.h"
#include "pico_dhcp_server.h"
int main(void) {
    // create DHCP server
    struct pico_dhcpd_settings s = { };
    s.my_ip.addr = long_be(0x0a280001); /* 10.40.0.1 */
    pico_dhcp_server_initiate(&s);
}

pico_dhcp_server_initiate函数在pico_dhcp_server.h:中声明

#ifndef _INCLUDE_PICO_DHCP_SERVER
#define _INCLUDE_PICO_DHCP_SERVER
#include "pico_dhcp_common.h"
#include "pico_addressing.h"
... omitted some declarations ...
int pico_dhcp_server_initiate(struct pico_dhcpd_settings *setting);
#endif /* _INCLUDE_PICO_DHCP_SERVER */

并在pico_dhcp_server.c:中实现了该方法

int pico_dhcp_server_initiate(struct pico_dhcpd_settings *setting)
{
    ...
}

在编译代码时，我得到以下错误：Undefined reference to pico_dhcp_server_initiate(pico_dhcpd_settings *)。我正在用一个Makefile编译，它看起来像这样：

# This file was automagically generated by mbed.org. For more information, 
# see http://mbed.org/handbook/Exporting-to-GCC-ARM-Embedded
GCC_BIN = 
PROJECT = networking_driver_test
OBJECTS = ./mbed-rtos/rtx/TARGET_CORTEX_M/TARGET_M3/TOOLCHAIN_GCC/SVC_Table.o ./mbed-rtos/rtx/TARGET_CORTEX_M/TARGET_M3/TOOLCHAIN_GCC/HAL_CM3.o ./USB_Ethernet/modules/pico_dhcp_common.o ./USB_Ethernet/modules/pico_dhcp_client.o ./USB_Ethernet/modules/pico_http_util.o ./USB_Ethernet/modules/pico_ipfilter.o ./USB_Ethernet/modules/pico_nat.o ./USB_Ethernet/modules/pico_udp.o ./USB_Ethernet/modules/pico_igmp.o ./USB_Ethernet/modules/pico_tcp.o ./USB_Ethernet/modules/pico_simple_http.o ./USB_Ethernet/modules/pico_http_client.o ./USB_Ethernet/modules/pico_icmp4.o ./USB_Ethernet/modules/pico_ipv4.o ./USB_Ethernet/modules/pico_dhcp_server.o ./USB_Ethernet/modules/pico_dev_loop.o ./USB_Ethernet/modules/pico_http_server.o ./USB_Ethernet/modules/pico_dns_client.o ./USB_Ethernet/stack/pico_socket.o ./USB_Ethernet/stack/pico_arp.o ./USB_Ethernet/stack/pico_frame.o ./USB_Ethernet/stack/pico_device.o ./USB_Ethernet/stack/pico_tree.o ./USB_Ethernet/stack/pico_stack.o ./USB_Ethernet/stack/pico_protocol.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_Semaphore.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_Event.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_List.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_Mutex.o ./mbed-rtos/rtx/TARGET_CORTEX_M/HAL_CM.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_Task.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_CMSIS.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_System.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_Time.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_MemBox.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_Robin.o ./mbed-rtos/rtx/TARGET_CORTEX_M/RTX_Conf_CM.o ./mbed-rtos/rtx/TARGET_CORTEX_M/rt_Mailbox.o ./main.o ./USB_Ethernet/USBCDC_ECM.o ./USB_Ethernet/modules/pico_dev_mbed.o ./USB_Ethernet/modules/pico_dev_mbed_usb.o ./USBDevice/USBDevice/USBHAL_RZ_A1H.o ./USBDevice/USBDevice/USBHAL_STM32F4.o ./USBDevice/USBDevice/USBHAL_LPC17.o ./USBDevice/USBDevice/USBHAL_Maxim.o ./USBDevice/USBDevice/USBHAL_LPC11U.o ./USBDevice/USBDevice/USBHAL_LPC40.o ./USBDevice/USBDevice/USBDevice.o ./USBDevice/USBDevice/USBHAL_KL25Z.o ./USBDevice/USBMSD/USBMSD.o ./USBDevice/USBSerial/USBCDC.o ./USBDevice/USBSerial/USBSerial.o ./USBDevice/USBMIDI/USBMIDI.o ./USBDevice/USBHID/USBMouseKeyboard.o ./USBDevice/USBHID/USBKeyboard.o ./USBDevice/USBHID/USBHID.o ./USBDevice/USBHID/USBMouse.o ./USBDevice/USBAudio/USBAudio.o ./mbed-rtos/rtos/Thread.o ./mbed-rtos/rtos/Semaphore.o ./mbed-rtos/rtos/Mutex.o ./mbed-rtos/rtos/RtosTimer.o 
SYS_OBJECTS = ./mbed/TARGET_LPC1768/TOOLCHAIN_GCC_ARM/retarget.o ./mbed/TARGET_LPC1768/TOOLCHAIN_GCC_ARM/system_LPC17xx.o ./mbed/TARGET_LPC1768/TOOLCHAIN_GCC_ARM/board.o ./mbed/TARGET_LPC1768/TOOLCHAIN_GCC_ARM/cmsis_nvic.o ./mbed/TARGET_LPC1768/TOOLCHAIN_GCC_ARM/startup_LPC17xx.o 
INCLUDE_PATHS = -I. -I./USB_Ethernet -I./USB_Ethernet/modules -I./USB_Ethernet/stack -I./USB_Ethernet/include -I./USB_Ethernet/include/arch -I./USBDevice -I./USBDevice/USBDevice -I./USBDevice/USBMSD -I./USBDevice/USBSerial -I./USBDevice/USBMIDI -I./USBDevice/USBHID -I./USBDevice/USBAudio -I./mbed-rtos -I./mbed-rtos/rtos -I./mbed-rtos/rtx -I./mbed-rtos/rtx/TARGET_CORTEX_M -I./mbed-rtos/rtx/TARGET_CORTEX_M/TARGET_M3 -I./mbed-rtos/rtx/TARGET_CORTEX_M/TARGET_M3/TOOLCHAIN_GCC -I./mbed -I./mbed/TARGET_LPC1768 -I./mbed/TARGET_LPC1768/TOOLCHAIN_GCC_ARM -I./mbed/TARGET_LPC1768/TARGET_NXP -I./mbed/TARGET_LPC1768/TARGET_NXP/TARGET_LPC176X -I./mbed/TARGET_LPC1768/TARGET_NXP/TARGET_LPC176X/TARGET_MBED_LPC1768 
LIBRARY_PATHS = -L./mbed/TARGET_LPC1768/TOOLCHAIN_GCC_ARM 
LIBRARIES = -lmbed 
LINKER_SCRIPT = ./mbed/TARGET_LPC1768/TOOLCHAIN_GCC_ARM/LPC1768.ld
############################################################################### 
AS      = $(GCC_BIN)arm-none-eabi-as
CC      = $(GCC_BIN)arm-none-eabi-gcc
CPP     = $(GCC_BIN)arm-none-eabi-g++
LD      = $(GCC_BIN)arm-none-eabi-gcc
OBJCOPY = $(GCC_BIN)arm-none-eabi-objcopy
OBJDUMP = $(GCC_BIN)arm-none-eabi-objdump
SIZE    = $(GCC_BIN)arm-none-eabi-size
CPU = -mcpu=cortex-m3 -mthumb
CC_FLAGS = $(CPU) -c -g -fno-common -fmessage-length=0 -Wall -fno-exceptions -ffunction-sections -fdata-sections -fomit-frame-pointer
CC_FLAGS += -MMD -MP
CC_SYMBOLS = -DTARGET_LPC1768 -DTARGET_M3 -DTARGET_CORTEX_M -DTARGET_NXP -DTARGET_LPC176X -DTARGET_MBED_LPC1768 -DTOOLCHAIN_GCC_ARM -DTOOLCHAIN_GCC -D__CORTEX_M3 -DARM_MATH_CM3 -DMBED_BUILD_TIMESTAMP=1432213479.57 -D__MBED__=1 
LD_FLAGS = $(CPU) -Wl,--gc-sections --specs=nano.specs -u _printf_float -u _scanf_float -Wl,--wrap,main
LD_FLAGS += -Wl,-Map=$(PROJECT).map,--cref
LD_SYS_LIBS = -lstdc++ -lsupc++ -lm -lc -lgcc -lnosys
ifeq ($(DEBUG), 1)
  CC_FLAGS += -DDEBUG -O0
else
  CC_FLAGS += -DNDEBUG -Os
endif
all: $(PROJECT).bin $(PROJECT).hex 
clean:
    rm -f $(PROJECT).bin $(PROJECT).elf $(PROJECT).hex $(PROJECT).map $(PROJECT).lst $(OBJECTS) $(DEPS)
.s.o:
    $(AS) $(CPU) -o $@ $<
.c.o:
    $(CC)  $(CC_FLAGS) $(CC_SYMBOLS) -std=gnu99   $(INCLUDE_PATHS) -o $@ $<
.cpp.o:
    $(CPP) $(CC_FLAGS) $(CC_SYMBOLS) -std=gnu++98 -fno-rtti $(INCLUDE_PATHS) -o $@ $<

$(PROJECT).elf: $(OBJECTS) $(SYS_OBJECTS)
    $(LD) $(LD_FLAGS) -T$(LINKER_SCRIPT) $(LIBRARY_PATHS) -o $@ $^ $(LIBRARIES) $(LD_SYS_LIBS) $(LIBRARIES) $(LD_SYS_LIBS)
    @echo ""
    @echo "*****"
    @echo "***** You must modify vector checksum value in *.bin and *.hex files."
    @echo "*****"
    @echo ""
    $(SIZE) $@
$(PROJECT).bin: $(PROJECT).elf
    @$(OBJCOPY) -O binary $< $@
$(PROJECT).hex: $(PROJECT).elf
    @$(OBJCOPY) -O ihex $< $@
$(PROJECT).lst: $(PROJECT).elf
    @$(OBJDUMP) -Sdh $< > $@
lst: $(PROJECT).lst
size:
    $(SIZE) $(PROJECT).elf
DEPS = $(OBJECTS:.o=.d) $(SYS_OBJECTS:.o=.d)
-include $(DEPS)

我不确定是什么原因导致了这个错误。我相信.c文件没有被编译，但我对Makefile语法非常陌生。可能是makefile中有什么问题吗？有人能帮我吗？