Watch out where you are repeating the pattern in Row 2. It sounds to me that you are repeating from the beginning of the pattern row. But you should start your repeat from PURL 2.
So it'd be ... k1, p2, twist, p2, twist, p2, twist ... etc. (keeping in mind that the twist represent 1 knit st and 1 purl stitch)...
Whereas if you do your repeat like this ... k1 p2 twist k1 p2 twist k1 p2 twist etc ... you're going to have that rogue purl st.
Make sense ??