System.MissingMethodException Error:

I have a label on my webform called lblMessage, I have removed the "WithEvents" from the declaration, which I always to on my controls that don't handle events, as it adds unnecessary overhead.

So, I test it and I get a System.MissingMethodException Error

Quote:

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Method not found: System.Web.UI.WebControls.DropDownList JHAProductComparison.ListFeatures.get_lblMessage().

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I am only referencing the .visible property of this control in the code-behind.
Is there a reason this keeps throwing an error?