Grrrr...or how can I be so thick?

A while ago, I had a giveaway and Rhona won.  I'm making her a 'little something' which Gaynor over at Stitchersanon very kindly designed for me.  I have been stitching the 'something' and finished a skein of red thread.  Without bothering to check what thread I needed I rushed upstairs to my spares and found a skein of DMC321.  I knew it wouldn't be from the new .321 as I have had it in my stash a while.  I dashed back downstairs, pulled out a length, snipped, threaded and started stitching away. After \\\\ (yes I stitch the other way, I'm left-handed) I squinted at it and said "blast" (or words to that effect!)  It is a completely different red to the one I had been using.  This morning I went to see if I had any more DMC321 and found another 4 skeins.  Amazingly, they were all the same as the last one I had got out.  Drat!  Well I had done too much to unpick and red thread is horrible to unpick as well as it leaves fluff everywhere so I decided to start again on a new bit of fabric.  I got my DMC321 out and started the design again.  After a few stitches, well about 50 or so, I looked at the stitches so far and thought - this would look so much better in DMC666.  I carried on stitching and then wondered what shade the other red in the design was.  I looked at my chart, ahhh, the other red IS DMC666 - ahhh, actually the colour I should be using is DMC666 - sooooo no wonder the 321 was the wrong colour, it was the wrong shade.  Guess what?  When I got a new skein of 666, it matched perfectly!  So the moral to this story is check your chart regularly, even the legend!  Thankfully, it means I can go back to the original piece of stitching and continue as this was much further along!  Doh!