Class Not Recognised as Return/Parameter Type
<p>I'm calling a simple method that receives an instance of one of my classes and returns another class instance. For some reason it doesn't recognise them in the method declaration but is fine with them within the method and before the method is called. Can't figure out a reason for this. Here is my code;</p>

<pre><code>public ReceiptResponse DownloadReceipt(ReceiptRequest request)
    {
        ReceiptResponse call = null;
        ...
    }
</code></pre>

<p><code>ReceiptResponse</code> and <code>ReceiptRequest</code> both throw errors in the <code>public</code> line, but the creation of <code>call</code> is fine for some reason. Here is one the classes (both are nearly identical);</p>

<pre><code>public class ReceiptRequest
{
    public String ClientID;
    public String PolNum;
    public String RecNum;  
}
</code></pre>

<p><strong>MY ERROR</strong></p>

<blockquote>
  <p>Error 16  The type or namespace name 'ReceiptRequest' could not be
  found (are you missing a using directive or an assembly reference?)</p>
</blockquote>

<p><strong>UPDATE</strong></p>

<p>I definitely have the required using statement because if I hover over <code>ReceiptResponse</code> on the creation of <code>call</code> line then it displays the using statment in the tooltip.</p>

<p>Why is this?</p>
