Phil,
You can see names in the window to the left of the forula bar, but a better place to view them is in the Insert|Name|Define dialog
box (you can also bring it up with Ctrl F3). This box shows worksheet level names and names that are local to the active worksheet.
The latter are distinguished by having the sheet name appearing to their right. In your code, you refer to workbook level names
without qualification ( Data, for example). You refer to worksheet level names by qualifying them with their sheet name
(Sheet1!Data, for example).
I suspect that your example refers to a name that is local to Sheet1. If so, your code should be:
Names("Sheet1!CellB3").Visible = False
In any case, check the Insert|Names|Define dialog box to ensure that you are referring to your name correctly. If the name does not
appear at all, we are talking about completely different things.