ASP.NET compilation error probably caused by Master Page

I have this code in the Page_Load of a master page:

    protected void Page_Load(object sender, EventArgs e)
        if (Request.Cookies["loggedinuser"] != null)
            loggedin.Visible = true;
            show_username.Visible = true;
            string theuser = Request.Cookies["loggedinuser"].Value;
            show_username.Text = theuser;
            notloggedin.Visible = true;            

this works fine, but when I create a page using this masterpage, I get the following error when i run it: (the error is in the attached image file).

'show_username' is a Label.
'loggedin' is a placeholder

Anyone have any idea what the problem is?
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You probably have your masterpage controls inside  asp:ContentPlaceHolder section?
In case your content page has declared content for this ContentPlaceHolder it'll override the content placeholder section in masterpage. Therefore you'll get the NullReferenceException.

Is it your intention to have masterpage controls overridden by content page? If not you could move them out from the ContentPlaceHolder section, then you'll not get the exception anymore.

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rob22888Author Commented:
Hello, the problem was that I had used a 'ContentPlaceHolder' rather than just a 'PlaceHolder'. Simple error but I was pulling my hair out over it! Thanks!
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