K2- Item Frontend Editing

Dear All,

I apologize for my poor English.

I write a K2 item from frontend editing form.
When I forget to select the category of the article item in the frontend editing form, my TWN2 site kick me to 403 page.

I suppose K2 usually alert "Item must have a Category" in pop-up window.

How can I fix this problem?

This also happens in default joomla ( 1.7 ) beez template and K2 component 2.5 RC as component itself is responsible for the error output so it is not template related.