Facebook achievement does not show image in the ticker

I have added some achievements to my FB app. Everything works fine, but the images of the achievements are not shown in the ticker.

I checked the achievements with the URL Linter and the image prop开发者_Python百科erty seems to be valid.

Does it take some time for Facebook to upload my images in their own system or have I made a mistake?

The images in the ticker have a URL but at this URL is no picture, when it should display the picture of the achievement. Here is link to my app.

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I have found the answer to my question:

Facebook does not use the images from a https recource.

I used this:

<meta property="og:image" content="http://imgurl.png"/>

instead of this:

<meta property="og:image" content="https://imgurl.png"/>

and it worked fine.