CD-R Multisession Overburning

Hey ppl. I need a little help with multisessioning a 800mb overburned
cd. The question is why can't I burn a multisession cd on an
overburned 800mb cd. Even if the data size is half of the total
capacity of the cd itself? I got reply from Ahead that it is just a
standart and not a hardware limitation, if so then there must be some
software which doesn't submit to the standart. If there's such
software please tell me and if not then tell me why I can't burn a
multisession. Ahh, almost forgot, my CDRW it LTR-52246S, it supports
overburning up to I think 99min so 800mb is not a problem.
Thanks in advance.