[flexcoders] Change textInput text colour when value negative in AS3?

[candysmate]

How can I access the text color of a textInput with AS3? I want to
make the text colour red for negative number display.

I tried:

if(int(stkFirmLevel.text) < 0)
  {
    stkFirmLevel.color = "#ff0000";
  } else {
    stkFirmLevel.color = "#000000";
  }

without success.