How to retrieve error about private key loading.

[Aro RANAIVONDRAMBOLA]

Hello,
I realize that when my program calls SSL_CTX_use_certificate_file, it
returns an error because the certificate does not match the private key. I
would to process this kind of error. SSL_get_error( ) does not treat this
case. I would like to know what is THE function wich enable me to extract
the errors type ( in my case I want to retrieve error like
SSL_ERROR_PVKEY_DOES_NOT_MATCH_WITH_CERT )
Thanks for your help.