Message popup with response string pops up twice

Hi,

I have a (really small) problem but it drives me gracy... In Teststand 2016 I used the message popup step with a response string and one single "OK" button,... everything works fine, the only problem is that this popup window pops up twice (independent if I change the default answer or not). There are not many options I can choose with one button: The "cancell" button is disabled (no button) and "Activate Control" and "Default Button" is set to Button1.

Any Ideas?

Thanks a lot.

Matthias