how do I get different random duration every time I run a simulation in SimEvents?

Hi,

I am modelling a simple queuing model in SimEvents including a queue block and a server. For the server I am using an event-based random number to generate random duration from a Gamma distribution. When I run the model it uses random number but, the next time I run it, the model again uses the same number and do not give a new set of durations. How can I make this happen? My model and the answer are shown below.

In Discrete Event Simulation when using stochastic distribution, the model should produce different answer each time, then by running a certain number of times it should converge to a constant answer.

I would appreciate any help.