Need help mapping form fields

We are using ReachForce with our forms.  It identifies company industries based on company names.  If a user inputs a company name that is not on the "Industry" picklist, the "Industry_M__c" picklist is displayed. I want that value mapped to the "Industry" field.  I am using the code below.  It works, but only some of the time.  I am completely flummoxed as to what I am doing wrong.  Any thoughts?

<script type="text/javascript">
MktoForms2.whenReady(function(form) {
    //listen for the validate event
    form.onValidate(function() {
        // Get the values
        var vals = form.vals();
        //Check your condition
        if (vals.Industry_M__c !== "") {
            (vals.Industry = vals.Industry_M__c);
        }
    });
});
</script>

Thanks in advance for any help!