JS errors when I upgrade from v2.0.1 to 2.5.3

I have tried upgrading an existing script to use v2.5.3 rather than v2.0.1 by replacing both the JS include and the CSS file refrence. I now however get a JS error when I load the page which reads "Can't move focus to the control because it is invisible, not enabled, or of a type that does not accept the focus"
The offending line is: textBox.element().focus();
textBox is an instance of AW.UI.Input;
It has these properties set:
textBox.setControlText("");
textBox.setControlImage("search");
textBox.getContent('box/text').setStyle('padding-left', '0px');
textBox.setAttribute("aw", "control");

the textbox is embedded in a grid using this line:
grid.setHeaderTemplate(textBox, 1, 1);
Thanks