routine problem with 2004 not 2000

here's one i have no idea what is causing the problem

the attached routine works well in acad2000
but has problems in 2004

maybe there's a sys variable that needs to be set in 04??

ps
this is to make 3d elbows for pipe or duct, etc.
try entering 20, 30, 5, 90 at the prompts respectively
then try small elbow numbers like 1, 3, 8, 45 - that's where 04 chokes

once it errors, it won't work until a new dwg is opened.

any ideas?

Thanks!
Richard