Quickform Custom Rule reset button problem

I have created a new user registration form using Quickform. I have included register(submit) and clear form(reset) buttons. I have also created a custom rule which checks to see if a login name already exists in the database. If the custom rule is executed and an error is found, then an error message is output indicating the user needs to pick another login name. When I select the clear form button, the form will not reset. The reset button works when the form is being populated for the first time or if a javascript error message pops up. Unfortunately,after a custom rule rejection(server side check) the reset button leaves all the previous values in the form and will not clear the form. Is this the expected behavior or am I missing something in the documentation. Regards Margo