function check_form(form_index) 
{
    error_message = "";

    if(document.getElementById('ddlMake_' + form_index).selectedIndex == 0)
        error_message += "Please select a make.\n";

    if(document.getElementById('ddlModel_' + form_index).selectedIndex == 0)
        error_message += "Please select a model.\n";

    if (!IsZipcode(document.getElementById('search_zip_code_' + form_index).value))
        error_message += "Please enter a valid zip code.\n";

    if(error_message != "") 
    {
        error_message = "Please Fix the following Field(s):\n\n" + error_message;
        alert(error_message); 
        return false; 
    } 
    
    return true; 
}