Cannot convert Class to ObservableCollection
<p>I'm trying to convert my class <code>AllStock</code> to <code>ObservableCollection&lt;AllStock&gt; stockList</code> but I get the following error:</p>

<blockquote>
  <p>The best overloaded method match for 'System.Collections.ObjectModel.Collection.Add(Haze.AllStock)' has some invalid arguments</p>
</blockquote>

<p>Here is my coding:</p>

<p>I create my Observable Collection -</p>

<pre><code>private ObservableCollection&lt;AllStock&gt; _stockList;
public ObservableCollection&lt;AllStock&gt; stockList
{
    get
    {
        if (_stockList == null)
            _stockList = new ObservableCollection&lt;AllStock&gt;();
        return _stockList;
    }
}
</code></pre>

<p>Inside my method -</p>

<pre><code>var allStock = await service.GetSysproStockAsync();
var stock = allStock.Select(x =&gt;
new AllStock
{
    Id = x.Id,
    ...
    MaterialThickness = x.MaterialThickness
});

stockList.Add(stock); //Error here - I want to add my 'var stock' to my ObservableCollection
dgSysproStock.ItemsSource = stockList;
</code></pre>

<p>Why would it be throwing out this error?</p>