ToolbarItem icon

I'm trying to add a Icon to a toolbaritem but when i do, the app on android crashes with an unhandled exception.
With only text it works like a charm.

Working code snippet:

ToolbarItems.Add(new ToolbarItem("Menu", null, () =>
{
IsPresented = !IsPresented;
}));

Non working code snippet:

ToolbarItems.Add(new ToolbarItem("Menu", "icon.png", () =>
{
IsPresented = !IsPresented;
}));

The icon is present because it is used in the app on other places.