Adding a custom field through Code Snippets doesn’t work

Hi, i have the somevproblems with the code to add new fields in wp-job-manager job form. It should be very simplex. It works if used in function.php, but doesn’t work using code snippets. below code:
`add_filter( ‘submit_job_form_fields’, ‘frontend_add_salary_field’ );
function frontend_add_salary_field( $fields ) {
$fields[‘job’][‘job_salary’] = array(
‘label’ => __( ‘Salary ($)’, ‘job_manager’ ),
‘type’ => ‘text’,
‘required’ => true,
‘placeholder’ => ‘e.g. 20000’,
‘priority’ => 7
);
return $fields;
}

Can you help me to understand what’s the matter? Thanks