p12 file and timestamp url

Hi guys

I was using an self-signed certificate to develop a small Flash CS6 plugin using the Creative Suite Extension Builder. Now I need to sign with my company certificate and when I try to use, this message without any explanation appears:

I'm not using the Time Stamp Certificate yet. I inspect this certificate using firefox (and Mac Keys) and everything is ok.

My question is: I'm using a "DigiCert Inc" certificate and I do not generate the p12 (was other guy who works with me). Where I can find some documentation about the p12 file and how I can generate a valid p12 to use in Creative Suite Extension Builder (maybe there is some limitation, I don't know...)? I spend almost 2 days in this task.

Thanks for all