Chevron pattern dc3tog

[AndiM09]

I am wondering if you need to make 1 or 2 chains when doing a dc3tog? I have seen people say 1, some say 2, and some say none. I am losing a stitch in my Chevron and I'm wondering if the dc3 tog chain is the problem. Thank you!

[Granny Square]

Um, zero?  

DC3Tog = make a partial DC, 2 loops remain on hook; in the next stitch make a partial DC, 3 loops remain on hook; in the next stitch, make a partial DC, 4 loops remain on hook, yo and pull thru all loops.  When you "Xtog" anything, each stitch of the x adds 1 loop to the hook that already has 1 loop to start with, so the next-to last step has x+1 loops on the hook before you pull thru all. 

DC3 together turns 3 stitch bottoms into 1 stitch top, so is a reduction of 2 to your stitch count.  In your chevron, this reduction is the valley; at the top of the hill, you are probably putting 3 stitches into 1, adding 2 stitches to your stitch count, which cancels out your valley.  For me, it's the hills in between that cause trouble - each hillside should be the same amount of stitches; it's not uncommon for 1 side of a hill to gain a stitch and the other to lose one, and then it compounds and starts to look snaggle toothed.

Edited to add - there is no rule about adding any amount chains to a 'tog' stitch automatically.  The whole point of a 'tog' is to reduce the number of stitches.     A pattern tell you to do a 'tog' and then some number of chains because it's part of a lacy design element, but then it would say so--If it doesn't tell you to chain, don't..