This way of connecting blocks (under "on Tick") should produce multiple buy trades, not just one. Why do you get only 1 trade?
You don't actually need that "Once per tick" block. Note that this block is a filter, not a driver. This block does not make the following blocks to run once per tick. Well, this is exactly what will happen if you have it under "on Tick", but for other reason. The way this block works is very similar to the way "OR" block works.
I don't know why don't get multiple trades, but block "No trade" is most probably needed at the top.
What do you want to happen? Because I don't really understand, something is missing for me...