Any transaction made on the blockchain requires a fee to complete the transaction. The most common reason for a transaction being declined or not able to complete is that there are not enough funds for the transaction (gas) fee. Generally, the fee is paid in the cryptocurrency blockchain that the specific type of coin or token resides on. For example, the Switch token resides on the Ethereum blockchain, so Ether (ETH) is required for the transaction (gas) fee.
Please note: transaction (gas) fees can vary hour by hour and day by day depending on how busy the network is at the time of attempted transaction.