Signatures on Trust document

by Will
(Camarillo, CA Ventura)

A very strange situation here: My father, prior to both his and my mother's death, set up a revocable trust. The admin for the trust ultimately left 'the business' but assured my father that the trust he created for him was valid no matter what.

My mother passed away in 2009 and my father in Dec, 2012. While reviewing a copy of the trust, I noticed that there are no notarized signatures on the page provided for them within the trust. I cannot believe that the man who created the trust for my parents did not advise them to sign it.

Well, they are both gone and obviously can't sign it, now. Does this mean the trust is legally invalid? If so what, if anything, can be done?

There is a house yet to be sold with 3 beneficiaries listed on the trust: myself and a brother and sister, but if the trust is,
in fact, invalid is there anything other than probate to look forward to?