The "display graph" and "display stacked graph" buttons at the bottom of the Latest Data page can become disabled while graphable items are still selected. This happens after the following steps:

1. Open a Latest Data page with at least two items.
2. Use the "select all" checkbox at the top to select all items.
3. Click either of the "display graph" buttons.
4. Use the browser's "back" button to return to the Latest Data page.
5. Deselect any item.

The buttons will now be disabled. If your page contains, say, 10 items, 9 are still selected.

This does not happen if the items are selected individually before displaying the graph.