我在MPLAB IDE6.4编译如下程序，老有BUILD FAILED！，不知为何？

winnie

#include        <stdlib.h>
#include <pic.h>
#include        <math.h>
#define  uchar unsigned char
ustep(unsigned int x,unsigned y)
{ unsigned int n;
  n=834/abs(x-y);
  if(n==0)
     n=1;
   else if(n>255)
     n=255;
  return(n);
}

main()
{   uchar m;
    m=ustep(1001,1000);
}
编译后的信息如下，且无法调试。
Executing: "d:\htsoft\ht-pic\BIN\PICC.EXE" -C -E"ABS.cce" "ABS.C" -O"ABS.obj" -I"D:\HTSOFT\HT-PIC\include" -Q -MPLAB -16C925 -D32 -Zg6 -O -W6
HI-TECH PICC COMPILER (Microchip PIC) V8.01 PL1
Copyright (C) 1984-2002 HI-TECH SOFTWARE
Serial number: HCPIC-00001
Licensed to  : C WJ
Executing: "d:\htsoft\ht-pic\BIN\PICC.EXE" -E"cv9-pridecc.lde" "E:\11sh\picctry\CV9PART\ABS.obj" -Q -MPLAB -16C925 -D32 -LL -PSECTMAP -W6 -O"cv9-pridecc.cof" -O"cv9-pridecc.hex"
HI-TECH PICC COMPILER (Microchip PIC) V8.01 PL1
Copyright (C) 1984-2002 HI-TECH SOFTWARE
Serial number: HCPIC-00001
Licensed to  : C WJ
Psect Usage Map:
Psect    | Contents                 | Memory Range
---------|--------------------------|--------------------
powerup  | Power on reset code      | $0000 - $0003
end_init | Initialization code      | $0004 - $0006
text0    | Program and library code | $0764 - $0771
text     | Program and library code | $0772 - $07B0
float_te | Arithmetic routine code  | $07B1 - $07FF
rbss_0   | Bank 0 RAM variables     | $0020 - $0028
temp     | Temporary RAM data       | $0070 - $0076
Memory Usage Map:
Program ROM   $0000 - $0006  $0007 (     7) words
Program ROM   $0764 - $07FF  $009C (   156) words
                             $00A3 (   163) words total Program ROM
Bank 0 RAM    $0020 - $0028  $0009 (     9) bytes
Bank 0 RAM    $0070 - $0076  $0007 (     7) bytes
                             $0010 (    16) bytes total Bank 0 RAM  

Program statistics:
Total ROM used      163 words (4.0%)
Total RAM used       16 bytes (9.1%)

BUILD FAILED: Mon Feb 09 17:37:11 2004

winnie

ustep(unsigned int x,unsigned y)       //没有定义返回类型
{ unsigned int n;
  n=834/abs(x-y);
  if(n==0)
     n=1;
   else if(n>255)
     n=255;
  return(n);
}

改：

uchar ustep(unsigned int x,unsigned int y)
{ unsigned int n;
  n=834/abs(x-y);
  if(n==0)                       
     n=1;
   else if(n>255)
     n=255;
  return (uchar)(n);
}