what's so hard about painting ONE wall brown??

I just moved my living room into the former classroom and the dining room into the former living room. I was excited to paint, decorate and fix things up a bit since it looks like we'll be staying in this house another year. My dear husband offered to go and get me chocolate brown paint to paint ONE wall of the living room. He came back with a gallon of paint that said "chocolate" on it and we all trusted that the label was correct. (first dumb mistake) I woke up early this morning to start painting. When I opened the can it looked very red to me but I figured that's the best they can do here and I'd just have to be satisfied. I "cut in" all the edges and was quite proud of how much I'd gotten done by 7:30 this morning. When Darrell got up and inspected, he realized it was oil-based paint, although he'd been very careful to ask several times if it was water-based. By then, the tray, brush and everything had to be thrown out because nothing would remove the dark red oil paint. When the stores opened up, he went downtown to another store to see if he could find true water-based, dark brown paint. He came home with a bucket of salmon-colored paint! I was horrified and said it was unusable. He said that's the darkest they had. The second trip downtown, I went with him (which is what I should have done in the first place)and chose another dark brown that looked more like what I wanted. After mixing it, the guy opened the lid and it was purple! Come on, this was becoming a comedy show. Then Darrell asked if he'd mix some brown into the salmon-colored paint and see how it looked. After adding brown three times, it came out quite dark and somewhat to my liking. Now I discovered that I'm going to need another gallon because it didn't cover very well. The guy gave me his number and told me to call him and he'll have another gallon ready for me. He wrote down what he did with the first batch and I'm holding my breath that he'll get the second right! Only problem is that it's Friday and everything closed at noon so I'll have to wait til tomorrow. Maybe I'll post a picture of the finished product when it's done.