Blazor CascadingParameter is always null

New to Blazor, having trouble getting a CascadingParameter to populate from my MainLayout.razor:

@code{    private Toasts Toasts { get; set; }}<Toasts @ref="@Toasts" /><CascadingValue Value="Toasts">    @Body</CascadingValue>

And Index.razor page:

[CascadingParameter]public Toasts Toasts { get; set; }public async Task PackageChanged(string value){   Toasts.Something(value); //Toasts is null here}

And finally Toasts.razor:

@code {    private string Message { get; set; }    public void Something(string message)    {        Message = message;        StateHasChanged();    }}@Message

This code below frustratingly works, but I'd like to cascade just the one component (<Toasts />) instead of the whole layout:

<CascadingValue Value="@this"><Toasts @ref="@Toasts" />    @Body</CascadingValue>

And then index:

[CascadingParameter]public MainLayout Layout { get; set; } public async Task PackageChanged(string value) {      Layout.Toasts.Something(value); //this behaves as expected }