ToolbarItem Icon not working on Android

Dear Collegues,

I am creating project in Xamarin.Forms as a part of my Master thesis project.
I have a XAML view:

<ContentPage.ToolbarItems>
        <ToolbarItem Text="Refresh">
            <ToolbarItem.Icon>
                <OnPlatform x:TypeArguments="FileImageSource"
                            iOS="ic_add_circle.png"
                            Android="ic_add_circle_black_24dp.png" />
            </ToolbarItem.Icon>


        </ToolbarItem>

        <ToolbarItem Text="Add" Order="Primary" />
    </ContentPage.ToolbarItems>

I have put resources in both Andorid nad iOS project:
Android:
Image may be NSFW.
Clik here to view.

iOS:
Image may be NSFW.
Clik here to view.

After running it on iOS it works great!

But on Android it is not Image may be NSFW.
Clik here to view.
System.NullReferenceException: Object reference not set to an instance of an object

Any ideas what can I be doing wrong?