Your CD Recorder must support the overburning feature. The Recorder must support this type of media as well. Some recorders support 80min media but will not support 90min or 99min media. You should make sure you have the latest version of Nero, though this is supported from Nero 5.0 and above.
And you need to have the latest firmware for your model recorder, as it will contain information to enable overburning, but most importantly, it will contain Read/Write strategies for new CDR and CDRW brand of media and can resolve many issues you may otherwise run into.
You MUST burn in Disc-At-Once or Disc-At-Once 96 write mode or you can not Overburn. The mutlisession mode is not possible, if you want to burn such CDs.
You MUST enable overburning in Nero's File - >Preferences -> Expert Features, or if you have Nero Express, do so from More -> Configure -> Expert Features.
And you must deactivate/disable Check for correct disc format from within Neros Files -> Preferences -> General, or from within Nero Expresss More -> Configure -> General settings.
When you enable Overburning in Expert Features, you should use the below settings based on the size of media you are working with:
For 80min media set to - 82:00
For 90min media set to - 89:30
For 99min media set to - 99:54:74