Electronic – using oscilloscope in Proteus AVR Simulator

Two issues come to mind:

1. Is the ground clip of your probe connected such that you get the shortest possible connection to the return of your signal source? (If the logic IC or FPGA has supply pins buffered with capacitors, connect your probe's ground clip directly to the ground node at these capacitors.)

2. Is your probe compensated? It's not enough to use a 1:10 probe for good signal quality, you also need to match the probe's capacitance to the scope input's capacitance. Related: This online tutorial, this answer and this answer.

I would start by disconnecting the square wave generator and replicating exactly what was done in the video. If you can make the sine wave appear, at least you know the rest of the VI is working.

You can also wrap the whole VI in a while loop and let it execute perpetually while you're fiddling with the DAQ view, instead of pressing play over and over again.