yiiactiveform is not a function what is the mesg

I am trying to submit a form and I am getting in firebug the following message

$("#form").yiiactiveform is not a function

What does this mean?

It means that the function yiiactiveform() cannot be found… could be that for some reason the file jquery.yiiactiveform.js is not included… this is automatically "published" by Yii by default in the assets folder…