Set a default association GPO not work

Hi,

We have 2012 DC and Win 10 clients. Since Edge is set to default program to open PDF, we want to change to Adobe Reader DC. I followed the solution 2 instructions in the URL below, however it won't work.

https://www.adobe.com/devnet-docs/acrobatetk/tools/AdminGuide/pdfviewer.html

On the client computers, GPO is applied but not work. Need help!!!

Thanks in advance! 

Grace