ASP.NET register a control from external dll on a page
<p>I am banging my head against the brick wall today.  I am porting a site I had developed on an old box across to a new dev env.  I have not just copied all the files as I didn't have a great file structure and some parts of the code needed to be removed as I went along.</p>

<p>Originally I had created a website (File -> New -> Web Site).  I wanted a file structure something like:</p>

<p><a href="http://stackoverflow.com/questions/446017/popular-folder-structure-for-build">http://stackoverflow.com/questions/446017/popular-folder-structure-for-build</a></p>

<p>So I created a new blank solution so the sln file was on its own, then added projects (various DLL projects) and am ASP.NET Web Application.</p>

<p>This last part seems to have caused me a few issues that have given me a headache.  As far as I understand (this could be a little limited), a webiste (as I first had) is different to the later type I created.  For example the App_Code folder part didn't work as before.  To solve that I created a seperate DLL for the webLibrary cs files and added a reference to it.</p>

<p>My problem now is how I register this on a page to be able to use the controls in it.  For example I have a control that inherits from TextBox, when it was in the App_Code folder I could use:</p>

<pre><code>&lt;%@ Register TagPrefix="sarg" Namespace="MyNameSpace" %&gt;
</code></pre>

<p>Then use</p>

<pre><code>&lt;sarg:SARGTextBox id="clienttitletxtbox" runat="server" OnTextChanged="textboxfiltering_TextChanged" AutoPostBack="true"&gt;&lt;/sarg:SARGTextBox&gt;
</code></pre>

<p>Now it is in its own DLL and namespace I can not figure out how to get it to work, I just keep getting warnings saying "Cannot resolve symbol 'SARGTextBox'".</p>

<p>It is probably really simple but I can no longer see the wood for the trees.</p>

<p>Thanks</p>
