Can't get a right gauge

Following pattern for Basic Mitten, children size 6-8 from a knitting book titled - ‘I can’t believe I’m knitting’.

Question is-

I tried to knit a gauge with Lion Brand Jiffy Mohair look yarn. This yarn calls for size 10 needles and 14.5sts = 4". I get 3 sts to an inch. Then I tried (from the book) size 5 then size 7 needles still come up with 3 or 4 sts to an inch.

The books gauge: with large needles in stockinette stitch. 20sts = 4". Been trying most needles to get a gauge. Can you help?

What am I doing wrong?

M

The yarn is too thick. You might get gauge if you go down small enough, but it’ll be too stiff. If there’s a smaller size of the pattern, use that with size 10s.