Master Page Problem

Hello Everyone,
    I had two master Page in my application. My Requirement is such that I have to place Label inside Master Page's ContentPlaceHolder and then access that Label in Content pages. How can I do that?? In Normal scenario, when there is one Master page & Label not placed in ContentPlaceholder,  I use
Label lblMasTitle = (Label)(Master.FindControl("lblMTitle"));
        lblMasTitle.Text = "Product";
and it works. But now when I do that, it gives me error message: "Object reference not set to an instance of an object".
Thanks in Advance.
 
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