Grafana Dashboard : Internal Server Error in OpenNMS

Hi @torkel @grafana-labs-team
Currently i have install Grafana 7.5.5 version for purpose of fetching OpenNMS data.
including install Grafana plugin - OpenNMS Helm- 6.0.0 version and data source
We are unable to fetch the OpenNMS horizen data in grafana throwing a error, which i have mentioned.

{
“request”: {
“server”: {
“id”: “cfd2288d18a3862763de0c7c14d0ad35”,
“name”: “OpenNMS Flow”,
“url”: “/api/datasources/proxy/1”,
“auth”: null,
“metadata”: {
“version”: {
“version”: “28.1.0”,
“dv”: “28.1.0”
},
“type”: {
“id”: 1,
“label”: “HORIZON”
},
“ticketerConfig”: {
“plugin”: null,
“enabled”: false
}
}
},
“params”: {
“N”: “10”,
“start”: “1634133631811”,
“end”: “1634220031811”,
“step”: “94323”,
“includeOther”: “true”
},
“method”: “GET”,
“url”: “api/datasources/proxy/1/rest/flows/applications/series”,
“hideFromInspector”: false,
“timeout”: 10000
},
“response”: {
“error”: “Internal Server Error”,
“response”: “Failed to execute query: java.lang.Exception: {“root_cause”:[{“type”:“parsing_exception”,“reason”:“Unknown aggregation type [proportional_sum]”,“line”:39,“col”:31}],“type”:“parsing_exception”,“reason”:“Unknown aggregation type [proportional_sum]”,“line”:39,“col”:31,“caused_by”:{“type”:“named_object_not_found_exception”,“reason”:”[39:31] unknown field [proportional_sum]"}}",
“message”: “Failed to execute query: java.lang.Exception: {“root_cause”:[{“type”:“parsing_exception”,“reason”:“Unknown aggregation type [proportional_sum]”,“line”:39,“col”:31}],“type”:“parsing_exception”,“reason”:“Unknown aggregation type [proportional_sum]”,“line”:39,“col”:31,“caused_by”:{“type”:“named_object_not_found_exception”,“reason”:”[39:31] unknown field [proportional_sum]"}}"
}
}

kindly reply on it.