Certificate not availble to select for encryption


I have recently installed Kleopatra and have successfully tested encryption and decryption in house.
Somebody has now sent me a public key and although it has imported successfully, I am unable to select it when trying to encrypt a file. It just doesn’t appear as an option even though I can see it from the main screen.

Where am I going wrong please?

SOLVED - Looks like it was a corrupt public cert.
Asks owner to resend and imported again.
Hey presto