Gnumeric is impressive, but...

First, how the Excel sheet looks like when the file is loaded:

How a name (containing "fen_graph" inside its definition) looks like when the file is loaded...
(please, notice the "#REF!")

And how that name SHOULD be!

The cell assigned to "fen_graph". Nothing fancy here: move along.

Now that's the correct aspect of the sheet!

When changing the value of the "fen_graph" cell, it changes the way the graph is drawn (noticed there are exactly 8 bars, did ya?)

That's all, folks!