This is about understanding that once one of your assumptions is wrong you have to assume there are others wrong also. Lately I was working to reconfigure a service which we had let slip out of date. There was nothing wrong with the old configuration expect it stop us from updating one minor component.

For the service being updated there was good documentation, all the information was there. The information was not in a step by step format but more of a descriptive format, it that's such a thing. The documentation even has explains so it does make it very easy understand. But when I had it set up it wasn't working how we expected it would.

Someone else on the team decide to give me a hand but with the difference in time zones they decide to help after their lunch right as I was going on my lunch (happens often and its not a problem). Before I went for lunch I sent them a link to the documentation that I was working from. 

Back from lunch I was greeted with "Oh, that section is not need unless your doing the third option", our setup was using the second option. From the documentation I understood this section was always needed no matter which of the three options you picked. After some to and fro, we came to the conclusion that their interpretation was correct.

Once we knew that my interpretation was incorrect the question then becomes what other interpretations and assumptions had I made which were also wrong? Again we read over the documentation questioning the meaning of every sentences. We came to one line were we both agreed on the meaning but looking closer there was one word, branch. Its a simple word but questioning our understanding of the word versus the documentation possible meaning showed we both misinterpreted that sentence. This misinterpreted was the reason we couldn't get the the reconfiguration to work.

Once you agree that one assumption was wrong or even in question, you have to assume others may also be wrong or questionably. The biggest problem in this case is you may not be able to see the assumptions that you are making. While getting help from someone else you need to be carefully that you don't feed them information that might lead them to the same assumption. In my case I am not sure we would have spotted the issue as fast if I hadn't went for lunch when I did letting the other team member read the documentation and make up their own interpretations and assumptions.