After creating nuget package dependency service not working in Xamarin forms project.

hi,

I have created a xamarin app to play audio from project folder and created app using dependency service play the audio file then it's working fine.
And I have create nuget package using the same source code but dependency service not working via configuring the created nuget package i have attached my entire source here.Any one kindly review it and help me how fix this.

use below link to download the file

Create a library to play the audio using dependency service. find the below link to download the source

https://drive.google.com/open?id=1amiuXEZ_QvxRHD4TmzEFKkPTs8Z-5e1O

sample create by using nuget package what i have developed.find the below link to download the source

https://drive.google.com/open?id=1I62ubkfnAMPDJLwpK5ZDRhlXg5abcIRS

thanks in advance