Facebook API, create adcreative error Cannot load post

Question

I am getting following error:

{"name":"FacebookRequestError","message":"Cannot load post: The post cannot be loaded and this can be due to many reasons. For example, the post might not exist, or it exists but is blocked, or it is a scheduled post (and therefore we are not allowed to deliver the post content as an ad)."}

While trying to create ad-creative through Facebook sdk. Please help me to fix it.

Here is payload sample in nodejs, i am using as example.

    params = {
        'name' : 'Sample Ad creative',
        'object_story_spec' : {'page_id': '<pageID>'},
        'asset_feed_spec' : {'images':[{'url': '<img url>'}
            ],'bodies':[
                {'text':'Sample text'},
                ],
            'titles':[
                {'text':'Sample text'},
                ],
            'descriptions':[
                {'text':'Sample text'},
                ],
            'ad_formats':['SINGLE_IMAGE'],
            'call_to_action_types':['LEARN_MORE'],
            'link_urls': [{'website_url':'<web_url>'}],
            'videos':[]},
    };