Step 1 - Determine the Recipient address
In order to send a coin or token, you need to have the correct recipient address. If the receiver provided the wrong address, the transaction will fail, or worst case your funds may get lost.
If you are sending BTC, make sure receiver provides a BTC address.
If you are sending ETH, make sure receiver provides an ETH address.
Step 2 - Need Sufficient Balance for Fees
As mentioned on the Sending Cryptocurrencies article, a small fee will always be required in one form or another before you can make transactions. Confirm if you have the necessary balance to pay for fees. This is always true for sending tokens for ETH, BNB and TRX.
Step 3 - Update your App
If you do not see a newer version, you can also hoin the Beta program here: https://trustwallet.com/beta. Please be advised that beta releases are experimental builds.
Step 4 - Re-Import/Reinstall the App
Try doing a re-import of your wallet first. This will re-sync your wallet without reinstalling the entire app. If this still does not work, then completely uninstall the app, reboot your device and then start over. Download the app and restore your wallet.
Step 5 - Report the Issue
After doing the above steps and you are still unable to send, please get all pertinent data and submit a ticket. You can use this link to submit details of your concern: https://support.trustwallet.com/hc/en-us/requests/new