iDEAL doesn't work? (ABN AMRO Netherlands)

Hi,

i just want to buy RP in league of legends store but Everytime when i try to purchase something with iDEAL, i enter my email, select bank and stuff but when i enter my accountnumber and cardnumber my e.dentifier2 doesn't start. I'm sure it's not the e.dentifier! So what I do is: Select my bank and enter my Email Adress(same adrress as my LoL account) and press Order details. Then i get a page to confirm my detailts, and press next. Now it asks again for my bank,and press next again. Then i enter my account and card number and press Ok and next, but then my e.dentifier doesn't start...

Does anybody know a fix?