What's so different about Windows I need to know?
You are not providing exact technical info and implying a generic malfunction, so let's try this again, shall we? Comp settings, exact footage types, system details, exact version of AE. For all we know, something trivial as a misconfigured tablet driver, a broken disk cache or generic hardware acceleration issues could be at play here as could be other stuff, but pardon me, there is really no point in getting lost in generics...
Well I don't have mote than that. I downloaded yesterday so its the latest version and I need to delete backgrounds to build composite presentations for children doing on-line presentations.
Some of the 'TOOLS' work but not the roto brushes.
I've no doubt its user error here but I can't think what. When everything else is seemingly working fine, the one feature I need, just isn't. Something isn't switched on.
I've wondered if its the version of Quicktime I'm using. AE states clearly it needs that for some of the functions, so I updated after the AE installation.. Could it be as simple as that?
Used Rotobrush on a Mac and on a Windows machine yesterday with no problems. The success and accuracy depend entirely on the image sequence or video. Without system details and AE version number we have no clue. I've never had Rotobrush fail to work on suitable footage. I have had footage that did not have enough edge detail to create a successful mask so I'd also suggest that you provide a frame or two of the footage that won't work.
That's starting to make sense. As I said, the version was as of the whatever is currently on the website now, as its less than 24 hours old so assume the latest.
The image not being defined is very possible. Thanks for the heads up.