Problem with the mod_jdonation with the textbox

I have a problem with the mod_jdonation. The same problem are on the demo site www.joomdonation.com , too (the module "Donate Us").

I write an other amount in the textbox, nothing mark the pre-defined amounts. I set the offline payment (the problem is with all options, too) and click the donate now-button.

On the next page I write the required informations, check the captcha and click on Process donation.
Although an other amount is in the textbox, I get this error: "Please choose from pre-defined amounts or enter your own amount in the textbox".

What is wrong?

Hi Michael,
To be honest, i am not sure with your idea, can you please submit ticket on category: Joom Donation and provide your site url with super admin account. I will check your Joom Donation setting and get back to you
Thanks
Dam