Error publishing a post marked promo in classmates?

Question

Classmates

Hello, I am making the following request to the API OK

request({
                                            url: `https://api.ok.ru/fb.do`,
                                            method: 'get',
                                            qs: {
                                                application_key: applicationKey,
                                                attachment: JSON.stringify(dataPost),
                                                format: 'json',
                                                gid: site_id,
                                                method: 'mediatopic.post',
                                                type: `GROUP_THEME_PROMO`,
                                                sig: sig,
                                                access_token: access_token,
                                            }
                                        }, (error, response, body) => {
})

It used to work fine, but lately I've been getting this error all the time:

error_code":456,"error_msg":"GROUP_RESTRICTION : errors.group.cannot_create_promo_moderation_topic

Tell me please, what could be the problem?