Add task to project does not behave correctly

When adding a task to a project, through this form : https://localhost:8443/projectmgr/control/EditProjectTasks?projectId=9000
the form behave weirdly. Upon the selection of a phase, you are redirected to another page before finishing to fill the form.

Step to reproduce :

• Go to this form : https://localhost:8443/projectmgr/control/EditProjectTasks?projectId=9000
• Select a phase from the dropdown
• See the immediate redirection

Guess of the problem : After some searches, it seems that the keyword 'void' used in most of the condition of the form doesn't work as it should. When you replace all the 'void' by 'null' , it seems to work as it should.