Combobox in vaadin table

Hi, I am new to Vaadin framewor. I am creating new vaadin application.

Problem statement: I have a table which has empno,empname and role. where role is Combobox which has list of items such as (Developer, Lead, Sr. Developer,…). if one record is assigned with Lead then, in reset of the records dosen’t show Lead item in combobox. It’s working when i am adding one record after another. But, if i want to change the role of the added record it’s not reflecting to already added record.

Thanks in advance.