Bidding works in 3 steps:

0 t/m 100 euro bids 5 euro
101 t/m 250 euro bids 15 euro
251 t/m …. with 25 euro
Watch for this!
It happens sometimes when u visit duivenveilen u automatic logged in on the website there because windows remember the password. Please note that your name or on top of the login window otherwise u make bids without a name these bids are then removed immediately, and are not considered as bids. If this happens you must first log out and log on the website ... Success ...