Both the Certificate file and the Private key file must be set
When Authenticode signing is enabled for a deployment project, both the certificate file and the private-key file must be specified. You must either specify both files, or disable Authenticode signing.
To correct this error
Enter the name of the certificate file (.spc) in the Certificate file field and the name of the private-key file (.pvk) in the Private key file field.
To disable Authenticode signing:
Uncheck the Authenticode signature check box.