We are using the Scrum for Team System template, and we found that the trend line was not showing up. At first I thought that we just didn’t have enough data and the report couldn’t generate a trend, but halfway through the sprint, it seemed like there was definitely an issue. The Trend Line was gone and the Capacity Trend (Baseline) was at zero. Apparently there’s a bug with the report that gets shipped with the original install and you can download an upgrade here. Just unzip the file and upload it to the Reporting Services server and tell it to replace the original. You may need to tell the report where the datasets are located, but it worked fine for me with no changes. Now we get all the information that we would need out of a burndown chart!