exp:channel:form Select Dropdown does not work in the Grid. Why? How to withdraw?

<select name="my_field_name">
{options:job}
<option value="{option_value}"{selected}>{option_name}</option>
{/options:job}
</select>

{exp:channel:form channel="name"}

{job_salary}
<select name="my_field_name">
  {options:job_salary:job_duration}
    <option value="{option_value}"{selected}>{option_name}</option>
  {/options:job_salary:job_duration}
</select>
{/job_salary}

{/exp:channel:form}