I really hate the Investopedia system. It keeps screwing me on trades. Like today, I submitted an order to purchase puts at market price and it never filled it. The stock is currently down 20% after hours. It's a market order! It should always execute on a decently liquid stock. Usually I would have a limit order, but this damn system doesn't fill orders so often I just wanted to make sure it would go through. So I missed out on $20,000 worth of gains so far. And to make things worse, I bet it's going to fill it tomorrow when the put prices skyrocket, so I'll possibly lose money on the damn thing instead of being way up.
I get that it's a free service, but if you're going to have a system it should be able to fill orders. It's really not that hard.