problem with int_rda()

[AZ APPS 1]

I'm using a pic18f4520 and alphacom as a terminal program.

I'm using the int_rda() to receive a character from the terminal, and then echo it back. The problem is that int_rda() never seems to get called. I never see a response on the terminal and the led that int_rda sets never turns on. When I use the getc and putc functions in main, I get the correct response on the terminal, so I know my rs232 interface is fine. I can also control the led in main, so I know the led is properly connected.

I've tried the routine with and without the #priority statement (which shouldn't be necessary when there's only 1 interrupt), and it doesn't affect the result.

Could someone please tell me why int_rda is not being called?

Here's my code:

#include <18F4520.h>
#device PASS_STRINGS = IN_RAM
#device HIGH_INTS=TRUE
#include <stdio.h>
#include <string.h>

#use delay(INTERNAL=8M, clock=32M)
#fuses INTRC//, DEBUG
#priority rda

struct portb_pin_map {
unsigned short led0;
unsigned short led1;
unsigned short led2;
unsigned short DTR;
unsigned short pic_mode;
unsigned short CTS;
unsigned short reserved;
unsigned short bit7;
} portb;

#locate portb = getenv("sfr:PORTB")

void scope() {
portb.led0=1;
portb.led0=0;
}

//rs232 link to computer
#use rs232(BAUD=9600, XMIT=PIN_C1, RCV=PIN_C0, BITS=8, PARITY=N)

void my_transmit_a(char *tx, int cr) {
int a=0;
while(tx[a]!=NULL) {
putc(tx[a]);
a++;
}
if(cr) putc(13);
putc(10);
}

char data=0;

#INT_RDA
void rda_isr () {
portb.led1=1;
data=getc();
putc(data);
}

void main(void) {
setup_oscillator(OSC_32MHZ);
delay_ms(1000);
disable_interrupts(global);
set_tris_a(0xF7);
set_tris_b(0xF0);
portb.led1=0;
enable_interrupts(INT_RDA);
enable_interrupts(global);
while(1) {
//data=getc();
//putc(data);
}
}

[PCM programmer]