Digital certificate - problem

[netfocom]

Hello, I installed Thunderbird ver.147 
I have a digital certificate /DC/, which I added according to the video tutorials.  
After trying to send a letter, I received an error message:
The message was not sent.
You want to encrypt the message, but the application cannot find a certificate for ...

I can't understand where this error is coming from.

[netfocom]

 Solved!
The problem was choosing the right security module from the many options available depending on the type of smart card.