I have just started using ADS. I want to simulate XOR, AND, OR blocks in ADS. I have used 2-input XOR, 2-input AND blocks from library. I have used time-domain vt_pulse source as input and used transient analysis. But after simulation I am getting zero output. It is happening for all AND, OR gates also. Even the clock generator from library is producing zero signal. I cant figure out what's the basic mistake I am making.