"Unknown Identifier : add"

[SomeKindofGamer]

I'm making a game in haxe
But every time i compile it says "Unknown Identifier : add"
Please help
This is the line of code which causes it:

var versionShit:FlxText = new FlxText(5, FlxG.height - 25, 0, ("Version " + ver), 12);
versionShit.scrollFactor.set();
versionShit.setFormat("VCR OSD Mono", 20, FlxColor.WHITE, LEFT, FlxTextBorderStyle.OUTLINE, FlxColor.BLACK);
add(versionShit);
Is there anything i'm doing wrong?

[Geokureli]

what class are you putting this in? what class does it extend? I take it you got this code from here. Note that this is in a class that extends FlxState, which extends FlxGroup, which defines the add method