Get crop with width and height using TypeMedia

Questions
1

So, i have

@{
	var mediaItem = Umbraco.TypedMedia(1236);
	if (mediaItem != null)
	{
		<img src="@Url.GetCropUrl(mediaItem, height: 300, width: 400)" />
	}
}

doesnt work… Any help :)?

This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/74800-get-crop-with-width-and-height-using-typemedia