The CreateFolder command is usually used to make folders below the current folder, and isn't available in This PC (as you can't make folders there).
(In this case you aren't trying to make a folder under This PC, but passing a full path to CreateFolder is a bit of a bonus feature, not the normal use of it. The check to see if the command is available is done before looking at the arguments to the command in this case.)
Here's a script-button which does the same thing, and is generalised to always open one folder on the left, the other on the right, and to create either folder if they don't already exist:
You could do it like this, but only in the next version. I found this sequence of commands caused problems due to a bug I fixed earlier for the next update:
Go /mypictures OPENINLEFT
Set SOURCE=Left
CreateFolder "Nexus6P" READAUTO=dual
Set UTILITY=filelog