Custom Icon doesn't show up for action in MainToolBar Follow

I am adding custom icon to my intellij plugin action.

<action icon="/video/videoicon.svg" class="actions.PopupDialogAction" description="Test Description" id="fetchSession" text="Fetch Session"/>

I can access this icon by pressing Command + Click, but I can't see the icon in the toolbar. It's shown as blank. What am i doing wrong?