Well, after spending over 4 years of getting my credit house in order, this is a first for me. I was DENIED a CLI from Discover due to LOW USAGE. I called customer service and she said that when the statements pulled, it shows a zero balance. She said she could see that I used the credit card (bought a KitchenAid over the range microwave and a KitchenAid double range), but I paid them off before the statement was cut. In order to get an Credit Line Increase, I've got to carry a balance.
I'm in the process of refinancing my mortgage and I have to keep my credit statements low right now and until November (that's when I'm scheduled to close on the refi).
So for me, this is a first -- to be denied (with good payment history) solely for low credit usage. 
I can attest you DO NOT need to post a balance on the statement, I have AZEOed this card for 5 years and have received CLIs on the card without a problem at all, there is something else in your profile that they are not liking or you may really not be using the card enough. I have spend several hundred a month on it in the 5% cats only for these years as well and have SD for a quarter when the cats are not inline with my spending.
Sorry for your CLI denial, but I can say welcome to that club
As gdale6 mentioned you shouldn't need to post a balance. I also pay my balance before the statement cuts, so it reports $0 balance. I received some CLI's. However, my last denial I received the same message regarding low usage. For a month and half after, I used my Discover Card as my daily driver, and then received my CLI at my next request.
Discos being stingy right now on the CLIs.. yes there are exceptions... Im thinking they just thew you a loose excuse, not necessirily the right or accurate one.... And take the CSR's explanation with a grain of salt.... Stick with the AZEO/Paying it off before statement, and hit her up after the refi is completed.....
Discovers kinda notorious of just throwing up a no soup for you at times when they just dont want to give you a CLI .....
"Not enough experience with current CL "
You do NOT need to post a balance to get a CLI increase with Miss Disco.... Do think they might like some use, but folks have gotten CLIs on SD'ed cards... and for a majority of the time, Discover is a PIF card for me... (not right now with a BT in tow)
-J
Thank you all for the replies. I am going to wait to request for a CLI after I've refinanced. Lowering my mortgage payments are of a greater priority right now. I plan to hit them up for an increase at the beginning of the new year. My credit limit with Disco right now is $18,500. After the refi, I plan to buy some furniture for both of the guest bedrooms.