simultion of simulink model

Hi all, I am trying to transmit a compressed video (with svc codec) via model simulink Wimax. In order to do that,I imported my bitsream from workspace to simulink. Then I buffered it to be able to enter to simulink model. The simulation works but for ever with non stop. And as I am trying to plot the Eb/N0 versus BER performance of my model Simulink and bring out the output (which is a vector of bits) from simulink to workspace, I need to the complete simulation of my model. But, the simulation doesn't stop, it runs hours und hours without stop. Actually, I haven't unterstand this problem as a beginner in Matlab-simulink. But, I am quiet sure that I need to see the end of my work to be able to analyse the performance and then correct if there is a problem. In addition to that, I am using bertool, but when I stopped my simulation, the bertool diplays 0 in the graph. please if anyone could help me, I will be grateful Thanks in advance