file_column help: want to pass along upload info to next state via form tags

Hello.

I have a page in which I inserted the option to upload a file in a form where other kinds of input text fields, check boxes, and radio buttons are being filled/clicked.

I followed the steps instructed here, http://www.kanthak.net/opensource/file_column/

except that when submitting the form, instead of saving the data entered, I display a confirmation page, followed by a final submit button.

It appears I lose some critical info between the first and second pages mentioned, in that I no longer have the necessary syntax to identify the uploaded file. I get an error when clicking submit to get to the third page, where I get an error like:

Do not know how to handle a string with value 'snapshot.tiff' that was passed to a file_column. Check if the form's encoding has been set to 'multipart/form-data'.

Because I merely passed along the data via hidden input tags. Multipart/form-data is set in all forms.

-Al