IE8/9 Error

[Bar F]

Cannot use this with IE8 / 9 so far... I get this error: 

SCRIPT5007: Unable to get value of the property 'push': object is null or undefined 

firebug-lite.js, line 8179 character 7

The line in question:

if(panel&&panel.panelNode){this.writeMessage(message,className)

}else{this.messageQueue.push([message,className])

}return this.LOG_COMMAND

};