"No root cert found" when evaluating my iPhone Distribution certificate

I'm having issues testing an app on my itouch device using adhoc distribution. The app was built using phonegap's build server. I'm distributing over the air using diawi.com's service to my itouch.The app starts to install just fine , but it looks like after the download portion is complete, comes up with a generic message saying "unable to install xxxxx at this time" or something close to that. I'm not clear what's causing the issue but started to suspect it might be my distribution certificate. From within Keychain Access on my Mac, when i choose to Evaluate my iPhone Distribution certificate, the Certificate Status is "Good" but the Evaluation Status reads "No root cert found". Strangely enough, i can click "View Certificate" and it shows me the certificate chain (up to Apple "Worldwide Developer Relations Certification Authority" and then up to "Apple Root CA"). I believe i have both of those certs installed in my Keychain, so i'm not clear why it say "No root cert found". I'm not certain this is what's preventing my app from installing on my itouch, but i wanted to chase this issue down in case it was the culprit. Any ideas on 1) Why i see "no root cert found" when i evaluate my certificate and 2) whether that might be the cause of my app not installing on my device. New to app development. thanks