I am trying to burn a RedHat Linux Enterprise 5 ISO to a DVD for a long long time. But each time I burn that Image to a DVD I get an eror with it. so I thought probably there is a problem with my imaging a dvd. but then I tried to install the os into a virtual machine with same image it works just fine. what could be the reason that i cant burn it properly. just to let you know i lost 6-7 dvd in this process

well the error is some thing like following:

Unable to read package metadata. This is may be due to a missing repodata directory. Please ensure that your install tree has been correctly generated. Cannot open/read repomd.xml file for repository: anaconda-base-200702081624.i385