Drop down menu (select) doesnt sends data

Hi there, i have this problem.

I can not make that the form sends the data when i use a drop down menu, but the email has sent succesfully.

If i put the data on to a radio button, it works fine. But i need to use a to many options, thats why its a must to use a drop down menu.

Every thing works fine, its just this problem.

Any idea to solve it will appreciated.

https://www.ads-software.com/plugins/contact-form-7/