Why do I need DirectCast?

In my immediate window I get the following:
?DirectCast(Me.FindControl("txtFName"), TextBox).Text.ToString().Trim()
Referenced object has a value of 'Nothing'.
?txtFName.Text
"Lisa"
So .. if I take out the DirectCast syntax, the value is passed but with DirectCast I get the Referenced Object has a value of nothing .. why and do I even need DirectCast here?

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