I have created a project using Block Diagram Schematic in Quartus II software. The project is a simple multiplexing system. I have downloaded the project into the target FPGA on Altera DE2 board. The project runs without problem and the LEDs show the blinking correctly. But I just can't Simulate the project using Quartus II Waveform Editor. So, what is the reason for that???? I mean if the project runs correctly that means there is no problem, so why not giving output in Simulation??? Thanks!