problems with signal(): "error 99, line 37: signal() already activated"

Hi,

I'm trying to generate a non-trivial pulse train using the debug scripting language, and I keep getting this error 99. Below is the script that generates the pulse. Whenever I start the script, I get this error from the title. Line 37 is the second call of the my_swatch() in the IR_send_mark function. I start the script by typing "IR_send_cmd(11)". Any hints?

// IR signal is fed to P3.2
DEFINE int IR_pin;
IR_pin = 2;

// duration of bits sent over the IR channel
DEFINE float low_bit;
low_bit=421.0e-6; // 421 us
DEFINE float high_bit;
high_bit=711.0e-6; // 711 us
DEFINE float start_bit;
start_bit=1184.0e-6; // 1184 us
DEFINE float stop_bit;
stop_bit=1184.0e-6; // 1184 us
DEFINE int IR_cycles_cnt;
IR_cycles_cnt= 6; // IR cycles in the IR mark
//DEFINE float instruction_time;
//instruction_time = ( (1/11.0592e6) * 12)

PORT3 |= (1 << IR_pin);  // initialize to high on the start of the debugger

SIGNAL void my_swatch(float pause)
{
   swatch(pause);
}

FUNC void IR_send_mark (void)
{       int i;

        i=0;
        while (i<IR_cycles_cnt) // cycles in the IR mark
        {
      PORT3 &= ~(1 << IR_pin);
          my_swatch(13.158e-6); // half of the 38 kHz cycle
      PORT3 |= (1 << IR_pin);
          my_swatch(13.158e-6); // half of the 38 kHz cycle
          i++;
        }
}

FUNC void IR_send_bit (float duration)
{
    IR_send_mark();
    PORT3 &= ~(1 << IR_pin);  // pull low to start the signal
        my_swatch(duration);         // hold low
    PORT3 |= (1 << IR_pin);   // return to high

}

FUNC void IR_send_byte(unsigned char byte)
{  int i;

   i=0; // 8 bits in byte, count downwards so that the MSB goes out
   while (i < 8)
   {  if (byte & (1<<(7-i)))
        IR_send_bit(high_bit);
      else
        IR_send_bit(low_bit);
      i++;
   }
}

FUNC void IR_send_cmd(unsigned int cmd)
{
  IR_send_bit(start_bit);
  IR_send_byte(cmd >> 8);
  IR_send_byte(cmd && 0xff);
  IR_send_bit(stop_bit);
}