hi i am attempting to convert an AVI to DVD format using this guide http://www.donstevenson.net/myguides/myguides.html

i have used this before to do the same task and sometimes had problems but always got them sorted (thanks to this forum) but i am currently stuck on step 8, when i have set up AC3 machine ready to convert the wav file to ac3 i click on the give me ac3 and nothing happens,

have i done something wrong? if so how can i fix it?