How to add annotations for non time based X-axis?

[AKo]

Hello,

I am trying to add annotations to a line chart, where the x-axis is a simple Id ( 1, 2, 3,....), a field named "RunId".  Each event label then should display (on mouse hover) the content of the field "Info", which is extracted in the annotation search. Both primary and annotation datasource include the field "RunId".
But no event is displayed, why ?

"viz_jcq0L1f3": {
			"type": "viz.column",
			"dataSources": {
				"primary": "ds_bNZHw3eE",
				"annotation": "ds_annotation"
			},
			"encoding": {
				"annotationX": "annotation.RunId"
			},...
                  ...
               }

"ds_annotation": {
			"type": "ds.search",
			"options": {
				"query": "index=someTestIndex source=*runids.txt | rex field=_raw \" (?<RunId>\\d+)\" |rex field=_raw \"info=\\\"(?<Info>[^\\\"]+)\" | dedup RunId | table RunId, Info"
			},
			"name": "Annotation Search"
		},