There are multiple tokens deployed to MainNet with the symbol "TBT". What you're looking at in MEW is the list of default tokens that have been registered with MEW and the TBT token specifically is referring to a different token contract.
If you look at the list of default tokens's registered with MEW (https://github.com/MyEtherWallet/ethereum-lists/blob/master/tokens/tokens-eth.json), you will see this:
{
"symbol": "TBT",
"address": "0xAFe60511341a37488de25Bef351952562E31fCc1",
"decimals": 8,
"name": "TBitBot",
"ens_address": "",
"website": "https://tbitbot.com",
"logo": { "src": "", "width": "", "height": "", "ipfs_hash": "" },
"support": { "email": "[email protected]", "url": "" },
"social": {
"blog": "",
"chat": "",
"facebook": "https://www.facebook.com/tbit.bot.5",
"forum": "",
"github": "https://github.com/tbitbot",
"gitter": "",
"instagram": "",
"linkedin": "",
"reddit": "https://www.reddit.com/user/tbitbot",
"slack": "https://tbotworkspace.slack.com",
"telegram": "",
"twitter": "https://twitter.com/tbit_bot",
"youtube": ""
}
},
Notice that it's a different contract address, so when you try to load your token balance you're actually viewing your balance of this TBT token.
Unless your token is registered with MEW, you can't use the default token list. You have to use the "Add Custom Token" button. Unfortunately, in your case it looks like MEW's UI to show a custom token checks the token symbol instead of the contract address and will error out if it's the same as a default token. So, it looks like you can't view it in MEW.