errorrrrrrrrrrr!!!!

i have problem in programming in keil uvision 3....
when ever i programme for interrupts,error L121 occurs when i build it(no prblm with compile) whenever i use interrupts...i am novice so was unable to understand it in uvision help...anyhelp??? i wrote the foll. programme:
#include<reg52.h>
sbit sw=P1^7;
sbit ind=P1^0;
sbit wave=P2^5;
void timer0(void) interrupt 1
{wave=~wave;
}
void main(void)
{
sw=1;
TMOD=0x02;
TH0=0xA4;
IE=0x82;
while(1)
{ind=sw;
}}