According to a course I am now taking there is one stitch you should not increase in. Can anyone tell me which one it is? Need answer to finish course.
Thanks, Frank 
Increasing
The only thing I can think of is that you should not work a lifted increase in a lifted increase.
Welcome Frank!
Hmm, that is a toughy. Yeah, like Marnie says, I try to avoid increasing twice in the same stitch, because it creates a hole.
The only other thing I can think of, is increasing in a stitch youāve just decreased, because āwhat would be the point.ā But of course, Iāve seen it done for a neat effect. IMHO, thereās really no āneversā in knitting! Thereās always those times when you break the ārules,ā either for effect, or for convenience.
Let us know what the ācorrectā answer turns out to be! Now youāve got us curious! 
Amy
Well, the particular increase that Iām refering to is the one where you knit a stitch and the stitch BELOW it. You are not supposed to work one on top of the other because youād basically work an increase with a stitch 2 rows down instead of one which would result in a rippled fabric.
See the Lifted Increase on this page:
http://www.wonderful-things.com/newknit4a.htm
Marnie, do you mean that if you worked it in the previous row or two, youāre not supposed to work it right above it on this row? Ahh yes, I think I get you now. I think you have the correct answer!
I tried doing that once, using that increase along the edge of a small project (I was making a knit heart, from the bottom up), and it gave a very tight edge along the side of the heart. I did the increase every other row, so it didnāt ripple, but it was definitely tight and pulled in, and I determined not to use that increase again in that way!
Frank, FYI, two more samples of this kind of increase are KLL and KRL on this siteās increases page. Their biggest advantage, that I know of, is that you can do the two side by side, for a double increase, that wonāt create a hole in the knitting.
Amy