For Beginner: Sample plugin works fine in DEV but not in PROD

Hello,

I am a beginner in MS CRM development.

To train myself, I have used the SDK Sample Calculate Price plug-in: https://msdn.microsoft.com/en-us/library/dn817877.aspx

All works fine with my Online DEV instance and the Plugin Registration Tool (debug included).

But when I add this plugin to my solution (assembly and steps), export them from Online DEV and import them into Online PROD, my plugin doesn't work in PROD.

After many searches and investigations, I can't find the good solution. Can you help me, please.

Many thanks.