Automatic Ad insertion not working

Hi,
So i inserted ads with your plugin and only one is showing up. I inserted ads after paragraph 2,6. Seperated them with a comma as shown in the documentation, but the ad image is only seen after the second paragraph. When i turn Label Blocks i see that Block 1 C=1 N=2 is created and is working, but the image doesn’t show up. Can you help me with this?

<!-- GPT AdSlot 1 for Ad unit 'responsive_unit' ### Size: [[400,250],[390,325],[340,280],[635,406],[300,250]] -->
<div id='div-gpt-ad-1535863-1'>
  <script>
    googletag.cmd.push(function() { googletag.display('div-gpt-ad-1535863-1'); });
  </script>
</div>
<!-- End AdSlot 1 -->

<!-- Start GPT Tag -->
<script async src='https://securepubads.g.doubleclick.net/tag/js/gpt.js'></script>
<script>
  window.googletag = window.googletag || {cmd: []};
  googletag.cmd.push(function() {
    var mapping1 = googletag.sizeMapping()
                            .addSize([700, 0], [[640, 400]])
                            .addSize([500, 0], [[440, 275]])
                            .addSize([425, 0], [[390, 325]])
                            .addSize([400, 0], [[360, 300]])
                            .addSize([0, 0], [[336, 280]])
                            .build();

    googletag.defineSlot('/22718203122/responsive_unit', [[440,275],[390,325],[360,300],[640,400],[336,280]], 'div-gpt-ad-1535863-1')
             .defineSizeMapping(mapping1)
             .addService(googletag.pubads());

    googletag.pubads().enableSingleRequest();
    googletag.enableServices();
  });
</script>
<!-- End GPT Tag -->

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