setFieldsValue not working in Select mode multiple

I am using antd version 4.3.3. I am trying to select multiple options in Select component which is in multiple mode like:

form.setFieldsValue({
  multipleSelectItem:[1,2]
});

in form element below:

<Form.Item
   name="multipleSelectItem"
   label="Multiple Select">
      <Select mode="multiple"
              showSearch
              ptionFilterProp="children">
                {options}
      </Select>
</Form.Item>

It is not working, can you guys please help me, where i am doing wrong ??