Why after migration of schemes (types issues and workflows), burndown chart lost commitment bars?

[Dionisio Valdes H]

Hi, why after migration with follow steps:

1. Change types issue scheme (for example, old type "new function", now is "story"; old type "subtask", now is "subtask analyst/developer").
2. Change the workflows scheme (for example, before, the project used two workflows with is states, now uses three workflows with different states and some old states).
3. Add new screen scheme for new subtaks types, to exist screen scheme.
4. and others steps like: configurate columns in board of project, add project to rules automated and minor jobs.

For a project managed for company and type scrum.

The burdown chart lost commitment bar and the value for commitment column only show zero value for all rows in table below of chart.  But, when click over a link of "sprint" column, in this table, the page open show the right data (for example, over sprint with 252 story point, you can view the chart and data table whitout problem).

In summary, we not lost data, then why the chart yes lost data? and the most important, whats i do for this not happend again? I must migrated other five project.

For you help, thanks a lot.