Release 8 does not read big tiff but we do not know if the image is big tiff. We are just guessing it might be without knowing important details about the image. Besides big tiff, another possibility is it could be something as unexpected (but fatal) as a limitation on TEMP space. Or it could be some special peculiarity in the TIF otherwise not supported in 8 (TIF is a very wide format and very few packages, if any, support all possible TIF content). Or you could be running release 7 or a have not updated to the current Release 8 build but are running with some prior build where some TIF problem was not fixed. I assume you are using 8 but that is not an assumption tech support would make.