That's interesting Sue. Maybe it's different for every individual.
My credit score just went up when I added another card, but didn't charge anything. Mortgage lenders might see that as potential debt, but for some reason it made my credit score go up by 10 points!
Equifax also has a tool where you can see what happens with your score if you do certain things. It will tell you what your score would be if you added another card, paid down a balance etc.
So, maybe it's different for everyone.
Barb, maybe you can try that tool on the website. It will tell you how to increase your score.
Good luck!