I'm using JDev 12.1.3.0.0
I follow this article https://docs.oracle.com/middleware/1213/adf/develop-faces/dvt-gantt-charts.htm#ADFUI542 (Section 26.5.4) to print the gantt chart. When I click the printer icon, the gantt chart is exported to a PDF file. But the employee column's value is not displayed (it should be the name of employee) (please see the image below).

Then I tried to change the width of that column but it isn't displayed anymore.

Any ideas is appreciate ? Thanks in advance.