Simulation DVD Burn Disabled in Nero 6.3.0.2 ?

Hi folks,
Just downloaded the latest Nero (6.3.0.2?) and found that simulation burn check box is disabled in DVD burning (CDR is OK). I am using NuTech DDR061 (firmware upgrade to DDR081). Any hints ?
Miho
Just downloaded the latest Nero (6.3.0.2?) and found that simulation burn check box is disabled in DVD burning (CDR is OK). I am using NuTech DDR061 (firmware upgrade to DDR081). Any hints ?
Miho