If your yarn is on the left needle, you can do the cast on. When you do the cable or knit cast on, you do it on the left needle. Once you cast the stitches on, then purl them with the rest of the stitches.
Check out Amy's video on cast ons and you'll see what I mean.
If all else fails, turn your needle around, cast on two and then turn it back.
"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