eboot编译出错！！

在移植2440的usb下载nk功能到2410的eboot中时：
s3c2410a_usbd.c文件中：三个函数定义和实现
BOOL UbootReadData (DWORD cbData, LPBYTE pbData);
BOOL InitUSB ();
void Isr_Init();

main.c文件中：
// For USB Download function.
extern BOOL UbootReadData (DWORD cbData, LPBYTE pbData);
extern BOOL InitUSB ();
extern void Isr_Init();

出现了这样的错误：
BUILD: [Thrd:Sequence:Type ] Message
BUILD: [01:0000000289:ERRORE] main.obj : error LNK2019: unresolved external symbol UbootReadData referenced in function OEMReadData

BUILD: [01:0000000290:ERRORE] main.obj : error LNK2019: unresolved external symbol Isr_Init referenced in function OEMPlatformInit

BUILD: [01:0000000291:ERRORE] main.obj : error LNK2019: unresolved external symbol InitUSB referenced in function OEMPlatformInit

BUILD: [01:0000000292:ERRORE] C:\WINCE500\platform\smdk2410\target\ARMV4I\retail\EBOOT.exe : fatal error LNK1120: 3 unresolved externals



网上查找解决办法说：在sources文件中加入
TARGETLIBS=\
$(_COMMONOAKROOT)\lib\$(_CPUINDPATH)\gsnull.lib 是我加入的语句 \
$(_COMMONOAKROOT)\lib\$(_CPUINDPATH)\fulllibc.lib \
但是还是出现了错误：
BUILD: [Thrd:Sequence:Type ] Message
BUILD: [01:0000000269:ERRORE] NMAKE : U1073: don't know how to make 'C:\WINCE500\PBWorkspaces\ARMSYS2410\WINCE500\smdk2410_ARMV4I\cesysgen\oak\lib\ARMV4I\retail\gsnull.lib'

BUILD: [01:0000000271:ERRORE] NMAKE.EXE -i -c BUILDMSG=Stop. NOLINK=1 NOPASS0=1 failed - rc = 2