1) seperate the 2 with a semi colon instead of a comma
2) The script I provided is an example, you need to modify the references of <formName>, <hidenElementName> and <selectListName> to use the correct values from your form page:
<formName> is the name of the form
<hiddenElementName> is the name of the hidden element
<selectListName> is the name of the select list.