Ceiling fan, one speed

I installed a Hampton Bay ceiling fan along with the wall switch controller. The fan only has one speed, the buttons for Hi, Med, and Low do not work. I suspect I did some wiring incorrectly, but do not know to trouble shoot it. Can anyone give me a systematic way of diagnosing and fixing this?

We had the same issue years ago when we installed a fan. Our problem wasn’t the wiring if I remember correctly. For us, the wall control would only work if the fan pull switch was in the “high” position. If we used the chain to put in medium or low, it would override the wall control. It’s been some time now, so I don’t remember how we figured it out, but once we did, I cut the chain short enough that you have to grab it with pliers if you want to use it.

Are the buttons on a remote?
If so, the remote probably hasn’t been synched with the receiver that sits in the fan.
Mine is like this. The remote died, and though I ordered a new remote and receiver I tried to get away with just installing the remote - and at the moment it is showing the same symptoms as yours. I need to take the fan apart enough to wire in the new receiver, and then it should work.
Look on the web for the synchronization procedure for your fan. If that doesn’t work, maybe the receiver has died.