Colspan in grid

Hi,

I try to merge / span some cells of one row in datagrid as decribed here

Result is that the following rows / columns be pushed together - see attached screenshot

I used follwoing code

<RadzenGrid @ref="grid" AllowFiltering="true" FilterCaseSensitivity="FilterCaseSensitivity.CaseInsensitive" AllowPaging="@paging" PageSize="20" AllowSorting="true" Data="@data" TItem="OpenItemModel" CellRender="@CellRender">

void CellRender(CellRenderEventArgs<OpenItemModel> args)
    {
        if (args.Column.Property == "Type" && args.Data.RowType == RowType.Header) 
            args.Attributes.Add("colspan", 3);
    }

Any idea whats going wrong?
Thanks and best regards
Arne

Hello,
no idea about this issue?
Thanks and regards
Arne