If PKI operations in iManager are not working, it could be because NetIQ PKI Services are not running on the Linux. Start the PKI Services by entering npki -1.
If you cannot create certificates, you need to ensure that the NICI module has been properly installed. See NetIQ eDirectory 8.8 SP8 Administration Guide. To verify if NICI is initialized, see NetIQ eDirectory 8.8 SP8 Administration Guide.