BarChart Tooptip problem after platform upgrade

We have upgraded from 8.0 to 9.1 and I've noticed the tooltip displayed when we mouse over a bar on a barchart is not displaying the value for the datapoint.  The bar shows the right value and the label on the tooltip is correct, but the value for it is not being updated.  See attached.

I'm not very familiar with the charting functions - most of these were done by someone else and I just maintain them so any help is appreciated.

Hi Cory,

I was not expecting that misbehavior to be related to the upgrade itself.

Still, my advise would be for you to see what list is feeding the Bar Chart webblock. 

That list is composed of  several data points (DataPoint structure). One of the fields of that structure is the "Tooltip".

You should confirm that you are setting it's content to the correct value for it to be displayed.

Does it helps?
I found that yesterday but wasn't sure how it worked so I just now started playing with it in debug.  The value that was getting assigned was empty (an attribute of a structure that was not being assigned anywhere prior).  I'm not really sure how this was (and is) working in production on V8, but it appears as though there is some default tooltip that was being used if no value was assigned (or if the value assigned is an empty string) - that value appears to be the "Label: Value".  It appears that changed somewhere going to V9.1.  It seems as though the default value assigned to the tooltip now is the "Label: 0".  At least that seems to be what I am seeing.

Also, what is the DataSeriesName used for?

Thanks for pointing me in the right direction.

I figured out the DataSeriesName: if provided, it displays a block with the color and then the name of the data series to be displayed at the bottom of the chart.

Data Series name is the concept used to have several data sets in the same chart, as you would define in Excel for example.

For example a chart that has the number of tickets, for date and for type.

You could have one series for each type and the x-axis would have the date.

AS you say that would get the chart to mark different types with diferent colors.