I have several sub-tasks within a story where I have set the effort estimation. However, the total of all efforts estimated on sub-tasks does not sum up and is not shown in the estimate field, which appears which appears at the right of each issue in the Backlog. As such it is also not reflected correct in the burndown chart.
How do I have to configure the board in order to have the sub-task efforts to be added as a total to the estimated field?