How to add an item of type "HTTP agent" to the chart in Zabbix?

Question

Zabbix

The point is the following.
I am collecting data from a server (closed application), which can send XML text via HTTP.
I added a data element, specified a URL, parsed it in the preprocessor (XML Path).
I get numbers at the output of the parser (number of sessions).
I don’t understand how to build a graph from this ... when adding an element to the graph, this element is not there =(

For the time being, I decided to temporarily display it on the dashboard as "Plain text", although the chronology is visible.
But you need to build a graph so that there is a correlation with the channel load .