To check it is installed correctly open the Settings, then Certificate Manager and it should be in the list. If not you might have a certificate with no CA or its signed by an untrusted CA.
Already checked that and they're there
Still getting the "Exchange server requires ..." error
Certs were originally imported as for "Server " & "E-mail"
Just remove the "E-Mail" entry as I read elsewhere that "server" is required. Also made no diff