I have an obviously HG+ kid who didn't score high enough on the Cogat to qualify for our district's gifted program. His teacher also refused to fill out a survey for him that listed potentially gifted traits because she didn't think she knew him well enough to answer the questions (he's never been one of the kids that stands out as obviously gifted unless you take the time to actually talk to him, and he also has a 2nd e). We appealed, and he got into the program.
What you can gain through an appeal is going to depend on your individual school district and possibly individual school program, but unless you have a reason to suspect an appeal would somehow hurt your chances of getting accepted at a later date or you're worried that you need to save your parenting advocacy for some other larger issue that might arise later, there's really nothing to lose in making an appeal. I was really surprised to learn when asking around at the time my ds was denied entry into the program that there were quite a few parents who'd had their children accepted because they were denied at first and then appealed... somebody from the district actually told me "it's the squeaky wheel" that gets the child into the program. BUT... that's our district. Other districts might not function the same way.
The other thing that helped us in our appeal - first, I researched to understand the possible reasons why my kid who scores sky-high on every other ability test he'd had scored as low as he did on the Cogat. I also asked him about the test so I had a good idea what types of things tripped him up. I never actually used this info in advocacy, but it was helpful for me to understand what was causing him to not "look" gifted to the school personnel. We were fortunate to have outside (private) ability testing for ds which was very difficult for the school to argue that he wasn't gifted. So my recommendation is to gather all the data you have (which can also include your observations of your ds' abilities), put it together in writing (don't include emotion, just facts), and send a written appeal (email is ok).
I'd also try to find out the name of the test that was administered to assess creativity - and find out if it's supposed to be timed.
Best wishes,
polarbear
