Hi Uday,
I just wanted say that I've got your message and I'm working on it. Basically, it seems that when I added the ACCA tool to RTWTools I forgot to update the right bits to make an item to do the ACCA calculation appear on the RTWTools menu.
Have you installed RTWTools using the instructions in the documentation file? If so, I can just give you an updated .sav file (to replace the one that was in the zip file you downloaded) and it should work fine from a new menu item. I will do a new release officially through the site, but I think the documentation file (which will obviously need updating) is on an old computer of mine that I need to dig out!
Cheers,
Robin