Sold ECH at $74.40

Today ECH was showing two of the four conditions for a trade exit, as defined in my previous post. The RSI(2) was above 70 and the Close was above the 5-day MA. In addition, RSI(4) was 53, very close to the target at 55.  In any event, my goal was two out of four, today it was reached, and the gain was 3.76% in two trading days.

I wasn't able to get the close price of 74.50 because... I don't really know.  Here's what happened.

At about 3:30 PM I tried to enter a stop limit order at 74.56, but Zecco rejected it, saying I didn't have enough shares to sell.  I checked the number, and it was correct.  Confused, I tried a few more times, and then freaked out a little bit and called customer service.  In a few minutes they told me that this happens when there is a previous sell order.  Duh! I had to cancel my stop loss order I had placed when I opened the position.  Then I entered a new stop limit order, which was accepted.  Oh, joy! But the last sale was staying at 74.39, and I wanted 74.40 at this point.  More than everything, I really wanted to sell, did not want to keep them for another day (which may have been a mistake, but goals are goals, I'm trying to be disciplined here).

So while I'm watching the last sale stay fixed at 74.39, my order is executed at 74.40, and I only find out at about 3:58 PM when I'm really ready to dump them at whatever price.  Two minutes later, somehow, the last sale becomes 74.50, although the 5-minute chart doesn't really reflect it.

Conclusions? What have I learned?

1. Must cancel all sale orders before attempting to enter a new one.
2. Must check order status after entering an order - not the last sale quote.
3. Selling is harder than buying.
4. Setting the sale price is tricky, still haven't figure out how to do it.