Fio + Xbee communication and variables transfer

I have changed the TX code like this

void loop() {

//increase the values to simulate variables change
  x++; 
  y++;
  z--;

  SEND(2,x,y,z); // send variables x,y,z with ID=2
  delay(z);
  SEND(3,a,b,c); // send variables a,b,c with ID=3
  delay(z);

}

so with each SEND() the delay will be decreased.

on the RX side I am printing to terminal just the z variable and the output is here:

9
9
8
8
7
7
6
6
5
5
4
4
3
3
2
2
1
1
0
0
255
255
254
254

so it looks like very short delay can be achieved.But when I set the delay manualy to 10ms the RX side is getting nothing again :frowning: