Tde sql

Hi guys,
I am new in the sql and still learning, but now I need your help. I got a task and need to use TDE on one database. I watch some videos on youtube and do accordingly. But none of the videos explain the error I'm getting.

I create master keys, the certificate and backup (.bak file), and when I want to restore the database on another server I want create a certificate but mssql tells me this problem:

The certificate, asymmetric key, or private key file is not valid or does not exist; or you do not have permission for it.

What should I do? I use google to search for this problem but didn't find the solution. I got permission on the admin level.
Please help me guys.

After this photo I try create new certificate and the error is : Msg 15208, Level 16, State 19, Line 11
The certificate, asymmetric key, or private key file is not valid or does not exist; or you do not have permissions for it.