#10010 errors encountered during linking;"WDT.out" not built和#10056 symbol "WDT_Counter"redefined:first defined in "./main.obj"

#include "MSP430G2553.h"
#include "WDT.h"
#include "GPIO.h"
//-----对状态机进行宏定义-----
#define IDLE 0
#define SHORT 1
#define LONG 2
#define COUNTER_THRESHOLD 50 /*长键判别门限*/
//-----全局变量-----
unsigned char  WDT_Counter=0; /*用于对按键按下时间进行计数*/
//-----在main函数前提前声明函数-----
void GPIO_Init();
void WDT_Init();
void Key_SM();
unsigned char LongClick_Dect();
void P13_OnShortRelease();
void P13_OnLongClick();
void main(void)
{
 WDTCTL = WDTPW + WDTHOLD; //关狗
    GPIO_Init();
    WDT_Init();
_enable_interrupts(); //开总中断
_bis_SR_register(LPM3_bits); //LPM3休眠
}