impossible activate AMP – Json googleanalytics

I tried to activate the function in AMP for googleanalytics, but there is nothing to do, from an error in the JSON code entry form
…. the system answer….. Unexpected token < in Json 0

are hours that I try everything … does not work

———————————————————
<script async custom-element=”amp-analytics” src=”https://cdn.ampproject.org/v0/amp-analytics-0.1.js”></script&gt;
<amp-analytics type=”gtag” data-credentials=”include”>
<script type=”application/json”>
{
“vars” : {
“gtag_id”: “<GA_MEASUREMENT_ID>”,
“config” : {
“<GA_MEASUREMENT_ID>”: { “groups”: “default” }
}
}
}
</script>
</amp-analytics>