Question about sending strings to firmata from processing

Hey guys,

Doing a school project and got stuck on using both serial.write to send a string value while using firmata at the same time. Is there any way to send a string value using firmata without serial.write?

Here is a part of my code:
(In setup())

arduino = new Arduino(this, Arduino.list()[6], 57600);

String portName = Serial.list()[6];
myPort = new Serial(this, portName, 57600);

Based on a condition, I want to send this to Arduino from Processing
(In draw())

myPort.write('H');

Was searching google for an answer but can't seem to find it. Help please! Thanks!

Attached is the error I get. The code is able to run but I get that error.

Screen Shot 2015-07-22 at 4.09.02 PM.png