Total Amount Field - need to 'zero it out' when form options change

I have forms that give users options that affect the Total Amount field.  I have noticed that the Total Amount field is not always cleared out when the user  'changes his mind' and selects different options.  The issue becomes noticeable when the user selects an option that prompts a message,  'option not currently available.'  In this case the Total Amount field remains populated with whatever value the form had most recently calculated.

Is there a way to add a 'clear form' button to the form?  Or is there a way to set the Total Amount field to 0 under certain circumstances?

Thanks,
-Joe

Hi Joe

The description of the issue is not very clear to me. Could you please send me link to the form and explain exactly what I need to do to see the error? I will check to see what's wrong and get it sorted

Regards,

Tuan

Tuan,
I'm not sure this is an error.  I see a behavior that I would like to change.  Here is how to get the result I don't like:
navigate to: josephz14.sg-host.com/index.php/register...rmediate-to-advanced
Scroll to the bottom of the page and select '5-Weeks' from the drop-down list. 
Choose any of the options from the rest of the controls that appear on the page until the Total Amount field has a value.
Now click 9-weeks from the control labeled 'Class Length. (This user might do this to see the schedule and costs of different class offerings)
You will see a message 'No Class Scheduled' but the Total Amount Field will contain a value and this is incorrect.
The result I want is for Total Amount to be set to '0' when 'No Class Scheduled'

You might ask 'why is it possible to choose the '9-weeks' option from Class Length when there is no class available.'  The reason is that I need to reuse Custom Controls across a number of forms in an effort to make ongoing maintenance easier. 

Thank you for taking a look at this,
Joe

Tuan,
I am working on this form this morning (Sunday 8:00 a.m. EST). Please do not try to look at this issue right now. Because I'm in the form, the instructions I provided to recreate my issue are not currently valid.
I will message you when I'm finished with the form.

Thanks you,
Joe

OK, thanks for the info Joe. I will look at it again when you are ready

Tuan