Toolbar Selection Feature.

Hello.

I need some help in adding toolbar selection feature. I've created JS function like in demo http://www.fckeditor.net/demo/toolbar :

function ChangeToolbar( toolbarName )
{
window.location.href = window.location.pathname + "?toolbar=" + toolbarName ;
}

After selecting another toolbar option tollbar changes but main editor text area disappear and I get the following error:
'this.linkedfield.value' is null or not an object.

Can someone here help me?

Thanks.