I'm more just curious as to how this happens as everything turned out fine and if it is a training issue or a system issue. First off--doing this on a Sunday morning so I know you don't typically get the most experienced agents. I was searching delta.com for flights ATL-LAS, I see several that require GUC for the upgrade (assuming the status on the website is correct) but a couple that are still available with a RUC. I quickly purchase a main cabin seat for one of the RUC flights and call in to apply the certificate and get the upgrade. Agent understands my request, puts me on hold and comes back and says since it a Delta one flight she couldn't confirm me with the RUC and would need a GUC. I told her that was strange for two reasons (1) I didn't think ATL-LAS was a Delta One market and website doesn't list any ATL-LAS flight as Delta One, and (2) I have found the identifiers (First avail with upgrade certificate versus first available with Global upgrade certificate) to be accurate in the past). She tried to insist she was right but I asked her to please check with supervisor. Of course she comes back and says something along the lines of "I don' t know why I'm seeing it as Delta one--but you are correct and we have applied your RUC and you are all set". Again a 20 minute process but all's well that ends well, but how could she have so much mis-information to begin with? What made her think/see it was a Delta One when the website clearly showed to me as First Class for all flight with several GUC flights and at least two that were RUC?