AWS SDK for PHP 1.5.3 -> my environment does not support the minimum requirements, but it does

Hi,

for the Video Module i need the AWS SDK. I installes the latest version (1.5.3) an all the required modules. In the status report i get the message:

Your PHP environment does not support the minimum requirements for the AWS SDK for PHP.

But the compatibility test says "Yes, you can!". Do i missunderstand something?
Screenshot

What can i do?