If you have an active bonus on your account, you may not be able to withdraw until the wagering requirements for that bonus have been met.
Wagering requirements specify how many times you need to wager the bonus amount before it becomes withdrawable. For example, a 100 € bonus with a 10x requirement means you need to bet a total of 1,000 € before withdrawing.
Bonus funds are kept in a separate balance and only convert to real withdrawable money once the wagering requirements are fulfilled.
To check your progress, go to My Account → Promotions → Active Promotions. For full details, see §4.10 of Betano's Terms and Conditions and the Bonus Terms page.