Sportsbet does not charge fees on deposits on the understanding that deposits will be turned over at least once, which means if you deposit $50 you'll need to bet $50 before you can withdraw the balance out of the account.
When trying to withdraw money out of your account you need to look at how much you can take out by looking at the Withdrawable Balance at the top of your My Account screen. The amount listed there reflects the amount that can be taken out of the account at the moment.
Please note that any funds deposited into your Sportsbet account needs to be Bet with before withdrawing.
You will also need to be Verified before you can withdraw funds.