You've got it, no one is perfect. Designers, knitters, editors, and publishers all have a hand in working up those pretty little booklets and sheets that eventually find their way to your LYS and into your pattern library. It can be really frustrating or confusing when some of the instructions don't seem to make sense or the numbers don't add up! It's good to understand that everyone makes mistakes, and you can (and will) find mistakes in some of your knitting patterns.
Do yourself a favor. When you get started on a new project check for any erratas before you cast on! The catch here is that mistakes in a pattern don't always appear on a slip of paper included with your pattern. You may have to search online.
The mistake may not have been noticed yet (for new patterns) or corrected yet. Or, you may have purchased the pattern before the errata sheet was printed. A quick online search before you start a project sometimes can avert frustration, frogging and even moments of nervous knitting breakdown.
Step 1: Read completely through your pattern or look through the entire pattern booklet in case there is an errata sheet included.
Step 2: Check the designer's website for published errata that hasn't made it into the pattern, booklet, or book yet.
Step 3: Check the publisher's website for the same reason.
Step 4: Try a search for the pattern you are going to begin on Ravelry or the internet itself. There are so many knitters out there that chances are good someone else is knitting the same pattern that you are. If they've found an error or are less than happy with the pattern, wouldn't you like to know about it?
Now you're ready to start your new project. We get many visits and phone calls from customers who are struggling with patterns. One of the first things that we do is check online for erratas. If only we all were in the habit of doing this to begin with it could save a lot of time and frustration!