well, i think that the data was just getting read in the wrong order. i sent a marker at the beginning instead of end of the values and it works now.
{
if (Serial.available()>=6) {
// If data is available to read,
processing = Serial.read();
if (processing == ';'){
board=Serial.read();
led=Serial.read();{
if(led >= 64)
led -= 64;}
red=Serial.read();
green=Serial.read();
blue=Serial.read();}
myMatrix.changeLED(int(board), int(led), int(red), int(green), int(blue));
}
thanks