Application Express :: Cannot Use Username Into Conditional Part Of Action Item

For our customer we have build a custom login page. The form we currently made has de following items:

- Username
- Password
- Select list for selecting the task type

When the customer enters his username, automatically the select list of the task type will be refreshed to get only the task type where the customer has the rights to do it. This part works...It can occur that a customer has only one task type (which is default) then we want to hide the select list. This part doesn't work

We used APEX version 4.1.1.What we did is:

- One action item to refresh the selection list (works)
- One action item to hide the selection list by starting the application (works)
- One action item to show the selection list only when the selection list has more than one result. For this part we used the conditional part of the action item (Function returning a boolean).

In the query (inside the function) we want to use the entered username, looking into the application in the session state I saw the correct username, but for some reason the function cannot use this entered username, it becomes empty. When I use a hardcoded username the code works.

Why I cannot use a username into the conditional part of the Action Item.