How to track scroll depth of Facebook Pixel in AMP page using amp-analytics?

Question

Any idea how to track scroll depth for Facebook pixel in AMP Page using amp-analytics?

I've tried but still failed to get & show depth parameter, below are my code:

 {
    "vars": {
        "pixelId": "123"
    },
    "triggers": {
        
        "scrollPings1": {
            "on": "scroll",
            "request": "event",
            "scrollSpec": {
                "verticalBoundaries": [25]
            },
            "vars": {
                "eventName": "ScrollDepth"

            }
        },

        "scrollPings2": {
            "on": "scroll",
            "request": "event",
            "scrollSpec": {
                "verticalBoundaries": [50]
            },
            "vars": {
                "eventName": "ScrollTracking",
                "content_name": "ScrollDepth"
            }
        }
    }