Hi,
Indeed, it seems your widget doesn't work that well.
However, I first have to tell you that what you want isn't currently possible. The order option allow to visualize the number of orders containing the given product but does give the number of sold product. This is something we may work on since the number of product sold can already been visualized through the listing and table reports.
About your problem, you should first try to create a new widget with the same parameters, if this on is old, it may be the source of the problem since we fixed few things.
If it doesn't work, I will need an access to your backend in order to debug the report tool since it's working on our test websites .