The submit button on wordpress stays at "please wait"

that's the link:

http://arcm.ch/conferences/

on wordpress, 

I've read some Q/A, but I cannot fix it. Any ideas?

Hello, I had to do a test submission on the embedded form on your website to check if I can reproduce the problem (sorry about that). And here's how it looked like from my perspective:

As you would have noticed, I managed to submit your form without issues. So, can you please give it another try? If it still won't submit, can you tell us if there's anything we can do on our end to reproduce the problem?

We can only investigate further if we are able encounter the issue beforehand. We'll wait for your reply.