upgrading ressource function

This issue happens when you define responsible that automatically generates assignment : then assignment is stored without a function (wich shoukd be mandatory).
If you change assignment at this step, then it is possible to update function value and save assignment.
If resource enters real work for this task, then "resource" and "Function" are locked, so you cannot define fucntion any more.

Ticekt #1370 recorded.

2 possible Workarounds :
1) define function directly in assingment table (with db tool)
2) remove real work from the task, define fiunction on assignment, re-enter real work.