problems with twitter card validator

Hi everybody,

I’m trying to add twitter cards (summary cards) to my website, but the twitter card validator doesn’t validate any of my pages (some get a red point, some other a jellow one, but none is approved).

I installed “WordPress SEO by Yoast”, I marked “add twitter card meta data” and insert my twitter Username under “social” and updated my profile with the twitter Username as well. It seems everything I need to do, but the validator doesn’t approve.

Any help?
The website is https://www.kanzleigallob.at

Thank you!