If you do a yo after a purl and before a knit just by leaving the yarn in front, you will get a yo, but a very tight one that wants to roll around over the needle. I did that for a long time and didn't realize it was wrong.
If that's the case, bring the yarn from the front over and around the needle to the front again. Then you'll get a better yo to work with.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry