-- This certificate has an incomplete certificate path.
-- This certificate has an incomplete certificate path. Either the certificate has been corrupted, or the entire certificate chain has not been correctly imported.

* The error indicates that the chain of certificates is not complete and not all the certificates (for e.g. Root) in the certification path

Therefore, in order to resolve this situation you may choose one out of the two options given below:

1) Request your partner to export and re-send the certificate again (preferably) in a PKCS #7 (.p7b) format with the option 'Include all certificates in the certification path if possible'.

2) Import this certificate in a browser like IE (Tools -> Internet Options -> Content -> Certificates -> Import). Once the certificate is successfully imported into the browser, Export it in .p7b format with the option 'Include all certificates in the certification path if possible'.