Timing out the session

I am attempting to set the session timeout value for a virtual server. What I want to do is to kill a session, once a user of some webservice grabbed some data. However, this is not working as expected. Below is a photo drawing out the scenario that typically tends to take case, in which, new sessions keep getting created for the same machine.

 

 

The red square denotes when a session was created, whereas the blue denotes when it will expire.

 

My configuration for the tcp profile looks as follows:

 

 

Am I missing something in making the RED and Blue squares closer in time? I.e Currently, the difference between the two is around 15 min. I want to make the Blue square (Expiration) much closer (if possible instantaneous) to expiring faster. My Java client that calls this webservice closes the connection, but I am not sure if there are any other packets I need to send for the F5 to undestand connection closing needs to take place.