UART communication

I am working on a project having three micro controllers....
Out of these three one is master and others are slave....
according to pin conditions of slave,it send some value which is recieve by the master
and showed at lcd....
When I use one of the both slave then it is working properly but when I use both the slave it is not working...
My programming for this..

void uart_init()
{ TMOD = 0x20; SCON = 0x50; TL1 = 0xFD; TH1 = 0xFD; TR1 = 1;
}

void uart_send(bit_8 value)
{ SBUF = value; while(!TI); TI = 0;
}

bit_8 uart_receive()
{ while(!RI); RI = 0; return(SBUF);
}

I am using same program in both slave becoz both have same circuit...but the value send by the slave are differ...