51单片机驱动DHT11温度传感器编译出错

51单片机驱动DHT11温度传感器编译出错，
Rebuild target 'Target 1'
assembling STARTUP.A51...
compiling dht11.c...
dht11.c(175): warning C290: missing return value
linking...
BL51 BANKED LINKER/LOCATER V6.22 - SN: Eval Version
COPYRIGHT KEIL ELEKTRONIK GmbH 1987 - 2009
"STARTUP.obj",
"dht11.obj"
TO "11"
*** FATAL ERROR L256: MODULE CONTAINS DUPLICATE SEGMENT NAMES
    SEGMENT: ?PR?_DELAY?DHT11
    MODULE:  dht11.obj (DHT11)
Target not created
请问是怎么回事?
以下是代码，帮看一下
#define uint unsigned int
sbit  P2_0  = P2^0 ;
sbit  P2_1  = P2^1 ;
U8  U8FLAG;
U8  U8count,U8temp;
U8  U8T_data_H,U8T_data_L,U8RH_data_H,U8RH_data_L,U8checkdata;
U8  U8T_data_H_temp,U8T_data_L_temp,U8RH_data_H_temp,U8RH_data_L_temp,U8checkdata_temp;
U8  U8comdata;   
U8  indata[5];
U8  count, count_r=0;
U16 U16temp1,U16temp2;
sbit wei1=P2^4;
sbit wei2=P2^5;
sbit wei3=P2^6;
sbit wei4=P2^7;
uchar code LEDData[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};
uchar data  display[5] = {0x00,0x00,0x00,0x00,0x00};
void Delay(U16 j)
{   
U8 i;
for(;j>0;j--)
{  
  for(i=0;i<27;i++);
}
}
void delay(unsigned int num)
{
  while( --num );
}
void  Delay_10us(void)
{
U8 i;
i--;
i--;
i--;
i--;
i--;
i--;
}
void COM(void)
{
U8 i;
for(i=0;i<8;i++)   
{
  U8FLAG=2;
  P2_1=0 ;  
  P2_1=1 ;  
  while((！P2_0)&&U8FLAG++);
  Delay_10us();
  Delay_10us();
  U8temp=0;
  if(P2_0)U8temp=1;
  U8FLAG=2;
  while((P2_0)&&U8FLAG++);

  P2_1=0 ;  
  P2_1=1 ;  
  if(U8FLAG==1)break;

  U8comdata<<=1;
  U8comdata|=U8temp;      
}
}

void RH(void)
{
   P2_0=0;
   Delay(180);
   P2_0=1;
   Delay_10us();
   Delay_10us();
   Delay_10us();
   Delay_10us();
   P2_0=1;
   if(！P2_0)  
    {
    U8FLAG=2;
    while((！P2_0)&&U8FLAG++);
    U8FLAG=2;
    while((P2_0)&&U8FLAG++);
    COM();
    U8RH_data_H_temp=U8comdata;
    COM();
    U8RH_data_L_temp=U8comdata;
    COM();
    U8T_data_H_temp=U8comdata;
    COM();
    U8T_data_L_temp=U8comdata;
    COM();
    U8checkdata_temp=U8comdata;
    P2_0=1;

    U8temp=(U8T_data_H_temp+U8T_data_L_temp+U8RH_data_H_temp+U8RH_data_L_temp);
    if(U8temp==U8checkdata_temp)
    {
       U8RH_data_H=U8RH_data_H_temp;
       U8RH_data_L=U8RH_data_L_temp;
    U8T_data_H=U8T_data_H_temp;
       U8T_data_L=U8T_data_L_temp;
       U8checkdata=U8checkdata_temp;
    }
   }
}
Disp_Temperature()
{
unsigned char  n=0;

display[4]=U8RH_data_H;
    display[4]=display[4]%100;
    display[3]=display[4]/10;
    display[2]=display[1]%10;
display[4]=U8T_data_H;
display[4]=display[4]%100;
display[1]=display[4]/10;
display[0]=display[4]%10;
if(！display[3])        
{
  display[3]=0x0a;              
  if(！display[1])      
    display[1]=0x0a;
}
wei1=0;
P0=LEDData[display[0]];
delay(5);wei1=1;
wei2=0;
P0=LEDData[display[1]];
delay(5);wei2=1;
wei3=0;
P0=LEDData[display[2]];
delay(5);wei3=1;
wei4=0;
P0=LEDData[display[3]];
delay(5);wei4=1;
}
void main(void)
{
  while(1)
  {
    RH();           
Disp_Temperature();
Delay(20000);
  }
}