When I started my OPAL socks I've told you that for the first time I had a ladders problem (maybe because this yarn is not very stretchy).
I think I found the solution to this! ^^
I worked with five needles (a sock on four needles and the working needle).
When I used my working needle (green one) like in the photo - OVER the previous needle (pink one) - I had ladders.
But, when I started to work with the fifth needle from UNDER the previous needle (pink one), the result was the smooth fabric! ^^
I don't know if you get what I mean, (I hope so), but that's what worked for me, so feel free to try it out if you encounter ladders problem in your socks of mittens. ^^