Problem validating digital signature

Hi!

When I try to validate a digital signature in Adobe Acrobat, I get two different responses, given the path I choose to validate the signature.

If I go through "Signatures panel" and check the validity of the certificate that signed the document, it tells me it's OK. If I click directly on the signature, and go through "Signature properties", it tells me the certificate signature can't be verified.

Can you help me?

Thanks in advance!

Mariana