Usually, the ‘Trade is disabled’ error is because:
1) The trading period is closed (weekends, holidays). Check Range of Markets for trading times and our news section.
2) The trading period is experiencing low liquidity. Exotic pairs are particularly affected.
3) A MetaTrader issue that can be resolved by changing Datacentres. To do so, click the ‘connection status’ in the bottom-right corner and select another Datacentre from the list.
4) The account is ‘inactive’. Demo accounts are archived after 90 days of inactivity.