You appear to be expecting the param('html_template'); to return an object but it is returning the literal string 'html_template' which is why you are getting the error that you are. The other problem with your code is that you are printing a header with the cookie straightaway whereas you actually need to be adding the the cookies to the headers you output before your main output. I really don't want to see the rest of your code, but you will need to add the cookie to a header elsewhere in your code,
/J\
