The reason for the shortfall is that you used a bonus--all bonus monies are non-withdrawable.
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You deposited $350, giving you a $1225 bonus. That $1225 was non-withdrawable and therefore removed from your total withdrawal.
You can see the terms and conditions, here: https://www.vegasstripcasino.com/rules.php
Unless otherwise specified by the Casino; all promotional bonuses are NON CASHABLE. Bonus money serves to enhance play and help to generate winnings but cannot be withdrawn as part of the winnings. The bonus will not be returned to the account but deducted from winnings by the Casino. At the point of cash out, all bonus money will be removed from the total amount of monies won.
I hope this clears things up.