You must have a TimeSeriesEEG datatype.
1. Click on the TimeSeriesEEG datatype to open the "Datatype details" popup.
2. In the opened popup select the "Visualizers" tab and after that press on the "Brain Activity with EEG lines".
3. In the opened visualizer press on the brain image from the right corner to open the controls page.
4. From the controls page pres the "Nodes" button. This action will display some nodes on the head drawn in the left side.
5. Try to select a green node using your mouse.
The node should be selected (its color should change in yellow) .
The select node operation will work fine after the left canvas is resized.