What does the "Not enough money on balance" error mean for a withdrawal transaction?

The "Not enough money on balance" error means that at the time of initiating the withdrawal, you did not have enough funds in the balance of the specific currency being withdrawn. You must top up the balance and reinitiate the withdrawal.
The system requires the balance to be available in the exact currency being withdrawn because automatic conversion is not possible for security reasons. You must convert the funds manually.