Problems on creating my certificate on quick start guide

I am getting error after Akash installation and creating account(Part 6 of the quick start guide in Quick Start Guide - Akash Guidebook). I’ve done every steps before the part such as installation, creating account, and purchasing AKT. The error code looks like this.

MacBook-Air ~ % akash tx cert create client --chain-id $AKASH_CHAIN_ID --keyring-backend os --from $AKASH_KEY_NAME --node $AKASH_NODE --fees 5000uakt

certificate file for address (my address) already exist. check it on-chain status? [y/N]: y

this certificate has not been found on chain. would you like to commit it? [y/N]: y

Error: rpc error: code = NotFound desc = account (my account) not found: key not found

Please somebody tell me if there was something I’ve missed or how I can solve the problem.

Thank you.

Seems like there is a issue with the key. Could you check if all variables are correctly set?

I think you didn’t set the shell variables properly!
Follow this guide: Click here

Or if you are beginner, you can simply install and use deployment ui tool: Click here