The graphics controller you have does support the Direct X 11.1 and it is enabled by default. You can check this information at the following link:
It is also important to mention that the driver we have for win 8.1 is a generic and beta driver. You can get the latest driver from our side at the following link:
The link you reference explicitly shows that the HD4000 does _not_ support DirectX 11.1. It appears the HD4200 is the oldest chip that supports 11.1. Am I missing something?